Merge pull request #13 from tampakrap/prerun_command

Set prerun_command with inifile instead of augeas
Refactor the install.pp

Replace $pe_ruby and $use_bundle variables with $provider variable
Rename r10k::install::ruby to r10k::install::gem to match the $provider value
Move bundle installation to r10k::install::bundle
Add Gentoo Portage support

It uses the package from Gentoo Portage
Introduces dependency to adrienthebo/portage Puppet module
Add default value for $gentoo_keywords