title: 'lib = "/usr/lib/R/library"' is not writable" while installing R Bioconductor package
body: <p>everyone!
  I'm trying to install Bioconductor package "cummeRbund" and constantly fail. I've tried 
  <code>biocLite("cummeRbund")</code> command with BiocInstaller enabled, <code>install.packages("cummeRbund")</code> and their variations with specified library address. The result is always </p>
  
  <pre><code>"Warning in install.packages(update[instlib == l, "Package"], l, contriburl = contriburl,  :
    'lib = "/usr/lib/R/library"' is not writable"
  </code></pre>
  
  <p>and r keeps offering me to use personal directory. What should I do to get rid of this pesky issue ("cummeRbund" is not the only one package that keeps failing to install)?</p>
  
  <p>My specs.: Ubuntu 14.04 LTS 64-bit, R version 3.2.2 (2015-08-14) -- "Fire Safety", Bioconductor version 3.2 (BiocInstaller 1.20.0)</p>