Adjust extension location for correct install path

With existing layout the built shared library will end up in the `./lib`
directory, but the expected location being checked is `./lib/vagrant`.
Adjusting the path within the extension directory results in the proper
adjustment to the installation path.

Rakefile

@@ -7,8 +7,7 @@ require "rake/extensiontask"
 $stdout.sync = true
 $stderr.sync = true
 
-Rake::ExtensionTask.new "vagrant_ssl" do |ext|
+Rake::ExtensionTask.new "vagrant/vagrant_ssl" do |ext|
-  ext.lib_dir = "lib/vagrant"
 end
 
 # Load all the rake tasks from the "tasks" folder. This folder

vagrant.gemspec

@@ -105,6 +105,6 @@ Gem::Specification.new do |s|
 
   s.files         = unignored_files
   s.executables   = unignored_files.map { |f| f[/^bin\/(.*)/, 1] }.compact
-  s.extensions    = ["ext/vagrant_ssl/extconf.rb"]
+  s.extensions    = ["ext/vagrant/vagrant_ssl/extconf.rb"]
   s.require_path  = 'lib'
 end