Improve the error message when a checksum can't be found for a given
ruby.

This could be becuase the user hasn't updated their list of rubies so I
add a line to show how to update your list of rubies.
Merge pull request #1493 from KeeperPat/documentation/clearer-error-log-when-checksum-is-not-found

Improve the error message when a checksum can't be found for a given ruby.
Add a small hook to run bundle install --local.
Merge pull request #1494 from envygeeks/patch-1

Add a small hook to run bundle install --local.
fix ruby mounting without default binaries, fix #1483
Merge branch 'master' of github.com:wayneeseguin/rvm