This commit adds a shared mutex to vmpooler API so that checkout requests can be synchronized across threads. Without this change it is possible in some scenarios for vmpooler to allocate the same SUT to different API requests for a VM.
During a rebase the vmpooler require was mixed up and still specified
lib/vmpooler. This commit removes this as well as the rubygems
requirement. Without this change vmpooler fails to work when built
because it cannot load lib/vmpooler.
This commit updates gemspec and Gemfile in preparation of a vmpooler release. To support this change the vmpooler executable is placed into a bin directory for inclusion in the gem. The license in gemspec is updated to Apache 2.0 to reflect the vmpooler project license.
