Resolve collision with unistd.h

On OSX 10.9, newer unistd.h libraries include an encrypt function, 
which this accidentally clobbers. There are still warnings from clang
but the error is now resolved with a rename of the function.
Update travis config

This adds two new rubies and removes EOL and unsupported ones.
Merge pull request #1 from martinisoft/fix_osx_build_errors

Resolve collision with unistd.h