Updating to release 1.5
Updating the docs to match version 1.5

1. Remove reference to the Mac package and recommend source install
2. Update the version number in the first CLI example
Adding Coyle et al. 2013 to list of publications using the Retriever
Updating CLI webpage to match v1.5
Removing whitespace at end of code blocks
Adding PLoS ONE article citation.
Adding instructions for how to run custom scripts
Merge pull request #92 from ethanwhite/document-custom-script-placement

Adding instructions for how to run custom scripts