Don't use Facter rvm_binary in providers

Facter facts are not re-evaluated for each install stage.  This commit
uses a different mechanism to locate the rvm binary.

Refs #34.

lib/puppet/provider/rvm.rb

@@ -0,0 +1,13 @@
+module Puppet
+  module Rvm
+    def self.rvm_binary
+      paths = [
+        '/usr/local/rvm/bin/rvm',
+        '/usr/local/bin/rvm',
+        '/usr/rvm/bin/rvm',
+        '/usr/bin/rvm'
+      ]
+      paths.find {|p| File.exist?(p)} || paths[0]
+      end
+  end
+end

lib/puppet/provider/rvm_gem/gem.rb

@@ -1,11 +1,12 @@
 require 'puppet/provider/package'
 require 'uri'
+require 'puppet/provider/rvm'
 
 # Ruby gems support.
 Puppet::Type.type(:rvm_gem).provide(:gem) do
   desc "Ruby Gem support using RVM."
 
-  commands :rvmcmd => Facter.value(:rvm_binary)
+  commands :rvmcmd => Puppet::Rvm.rvm_binary
 
 
   def ruby_version

lib/puppet/provider/rvm_gemset/gemset.rb

@@ -1,8 +1,10 @@
+require 'puppet/provider/rvm'
+
 # RVM gemset support
 Puppet::Type.type(:rvm_gemset).provide(:gemset) do
   desc "RVM gemset support."
 
-  commands :rvmcmd => Facter.value(:rvm_binary)
+  commands :rvmcmd => Puppet::Rvm.rvm_binary
 
   def ruby_version
     resource[:ruby_version]

lib/puppet/provider/rvm_system_ruby/rvm_system_ruby.rb

@@ -1,7 +1,9 @@
+require 'puppet/provider/rvm'
+
 Puppet::Type.type(:rvm_system_ruby).provide(:rvm) do
   desc "Ruby RVM support."
 
-  commands :rvmcmd => Facter.value(:rvm_binary)
+  commands :rvmcmd => Puppet::Rvm.rvm_binary
 
   def create
     rvmcmd "install", resource[:name]

manifests/passenger/apache/centos/post.pp

@@ -11,7 +11,7 @@
 ) {
 
   exec { 'passenger-install-apache2-module':
-    command   => "$rvm_binary $ruby_version exec passenger-install-apache2-module -a",
+    command   => "$rvmpath/bin/rvm $ruby_version exec passenger-install-apache2-module -a",
     creates   => "${gempath}/passenger-${version}/ext/apache2/mod_passenger.so",
     logoutput => 'on_failure',
     require   => [Rvm_gem['passenger'], Package['httpd','httpd-devel','mod_ssl']];

manifests/passenger/apache/ubuntu/post.pp

@@ -12,7 +12,7 @@
 
   exec {
     'passenger-install-apache2-module':
-      command   => "$rvm_binary ${ruby_version} exec passenger-install-apache2-module -a",
+      command   => "$rvmpath/bin/rvm ${ruby_version} exec passenger-install-apache2-module -a",
       creates   => "${gempath}/passenger-${version}/ext/apache2/mod_passenger.so",
       logoutput => 'on_failure',
       require   => [Rvm_gem['passenger'], Package['apache2', 'build-essential', 'apache2-prefork-dev',