fix rebuilding config for mruby, fix #2749
Merge branch 'master' of github.com:wayneeseguin/rvm
use last definition of ruby in Gemfile and .versions.conf, fix #2745
add bundler to list of required gems only when it is needed, fix #2747
speed up checking if required gems are installed, update #2747
builtin command -v ruby or true, update #2741
update tests
allow index.txt in path for checking for remote binaries, update #2743, update jruby/jruby#1607
set some LANG on travis when not set