Ruby Version Manager

[Konstantin8105]

Error, see https://travis-ci.org/elliotchance/c2go/jobs/308870512:

$ if [ "$TRAVIS_OS_NAME" = "osx" ]; then
    rvm get head
  fi
  
Downloading https://get.rvm.io
Downloading https://raw.githubusercontent.com/rvm/rvm/master/binscripts/rvm-installer.asc
Verifying /Users/travis/.rvm/archives/rvm-installer.asc
gpg: Signature made Sat Sep  9 19:49:18 2017 GMT
gpg:                using RSA key E206C29FBF04FF17
gpg: Can't check signature: No public key
Warning, RVM 1.26.0 introduces signed releases and automated check of signatures when GPG software found.
Assuming you trust Michal Papis import the mpapis public key (downloading the signatures).
GPG signature verification failed for '/Users/travis/.rvm/archives/rvm-installer' - 'https://raw.githubusercontent.com/rvm/rvm/master/binscripts/rvm-installer.asc'!
try downloading the signatures:
    gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
or if it fails:
    command curl -sSL https://rvm.io/mpapis.asc | gpg --import -
the key can be compared with:
    https://rvm.io/mpapis.asc
    https://keybase.io/mpapis
/Users/travis/.rvm/scripts/functions/cli: line 243: return: _ret: numeric argument required

Correct https://travis-ci.org/elliotchance/c2go/jobs/307085446:

$ if [ "$TRAVIS_OS_NAME" = "osx" ]; then
    rvm get head
  fi
  
Warning! PATH is not properly set up, '/Users/travis/.rvm/gems/ruby-2.0.0-p648/bin' is not at first place,
         usually this is caused by shell initialization files - check them for 'PATH=...' entries,
         it might also help to re-add RVM to your dotfiles: 'rvm get stable --auto-dotfiles',
         to fix temporarily in this shell session run: 'rvm use ruby-2.0.0-p648'.
Downloading https://get.rvm.io
No GPG software exists to validate rvm-installer, skipping.
Downloading https://github.com/rvm/rvm/archive/master.tar.gz
Upgrading the RVM installation in /Users/travis/.rvm/
    RVM PATH line found in /Users/travis/.mkshrc /Users/travis/.profile /Users/travis/.bashrc /Users/travis/.zshrc.
    RVM sourcing line found in /Users/travis/.profile /Users/travis/.bash_profile /Users/travis/.zlogin.
Upgrade of RVM in /Users/travis/.rvm/ is complete.
Upgrade Notes:
  * RVM 1.30 simplifies behavior of 'rvm wrapper' subcommand
RVM reloaded!