title: Parsing error when ingesting csv data into zipline using csvdir
body: <p>I am loading csv files using csvdir bundle in zipline. It is giving a "ValueError: Error parsing datetime string "A.csv" at position 0" error. How can this be resolved?</p>
  
  <p>When I load it directly using pandas, it loads fine:</p>
  
  <pre><code>&gt;&gt;&gt; Acsv = pd.read_csv("D:/work/tmp/hData/bundles/data/NYSE_dat/A.csv", parse_dates=[0], infer_datetime_format=True, index_col=0)
  &gt;&gt;&gt; Acsv.head()
               open   high    low  close   volume  dividend  split
  date                                                            
  2014-06-18  58.86  59.32  58.53  59.27  1114700       0.0    1.0
  2014-06-19  59.20  59.54  58.15  58.62  3149500       0.0    1.0
  2014-06-20  57.95  59.06  57.84  58.77  2027500       0.0    1.0
  2014-06-23  58.71  58.86  57.97  58.11  1435600       0.0    1.0
  2014-06-24  58.03  58.49  57.58  57.65  1125800       0.0    1.0
  </code></pre>
  
  <p>Here is the code error with the code:</p>
  
  <pre><code>&gt;&gt;&gt; CSV_BUNDLE_NAME = 'NYSE_dat'
  &gt;&gt;&gt; from zipline.data import bundles
  &gt;&gt;&gt; os.environ['ZIPLINE_ROOT'] = "D:/work/tmp/hData/bundles" 
  &gt;&gt;&gt; injst_func = bundles.csvdir.csvdir_equities(['daily'], CSV_BUNDLE_NAME)
  &gt;&gt;&gt; bundles.register(CSV_BUNDLE_NAME, injst_func)
  &lt;bound method CSVDIRBundle.ingest of &lt;zipline.data.bundles.csvdir.CSVDIRBundle object at 0x000000001CFC82E8&gt;&gt;
  &gt;&gt;&gt; bundle_data = bundles.load(CSV_BUNDLE_NAME)
  Traceback (most recent call last):
    File "pandas/_libs/tslib.pyx", line 1702, in pandas._libs.tslib.convert_str_to_tsobject
    File "pandas/_libs/src/datetime.pxd", line 119, in datetime._string_to_dts
  ValueError: Error parsing datetime string "A.csv" at position 0
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "pandas/_libs/tslib.pyx", line 1732, in pandas._libs.tslib.convert_str_to_tsobject
    File "pandas/_libs/tslibs/parsing.pyx", line 99, in pandas._libs.tslibs.parsing.parse_datetime_string
    File "C:\Users\Raja\.conda\envs\TradingEnv\lib\site-packages\dateutil\parser\_parser.py", line 1356, in parse
      return DEFAULTPARSER.parse(timestr, **kwargs)
    File "C:\Users\Raja\.conda\envs\TradingEnv\lib\site-packages\dateutil\parser\_parser.py", line 648, in parse
      raise ValueError("Unknown string format:", timestr)
  ValueError: ('Unknown string format:', 'A.csv')
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "C:\Users\Raja\.conda\envs\TradingEnv\lib\site-packages\zipline\data\bundles\core.py", line 486, in most_recent_data
      key=from_bundle_ingest_dirname,
    File "C:\Users\Raja\.conda\envs\TradingEnv\lib\site-packages\zipline\data\bundles\core.py", line 123, in from_bundle_ingest_dirname
      return pd.Timestamp(cs.replace(';', ':'))
    File "pandas/_libs/tslib.pyx", line 390, in pandas._libs.tslib.Timestamp.__new__
    File "pandas/_libs/tslib.pyx", line 1549, in pandas._libs.tslib.convert_to_tsobject
    File "pandas/_libs/tslib.pyx", line 1735, in pandas._libs.tslib.convert_str_to_tsobject
  ValueError: could not convert string to Timestamp
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "C:\Users\Raja\.conda\envs\TradingEnv\lib\site-packages\zipline\data\bundles\core.py", line 521, in load
      timestr = most_recent_data(name, timestamp, environ=environ)
    File "C:\Users\Raja\.conda\envs\TradingEnv\lib\site-packages\zipline\data\bundles\core.py", line 497, in most_recent_data
      timestamp=timestamp,
  ValueError: no data for bundle 'NYSE_dat' on or before 2019-07-10 03:03:42.161500+00:00
  maybe you need to run: $ zipline ingest -b NYSE_dat
  </code></pre>