SemVer 2 support
Forgot some tests
Merge pull request #134 from distantcam/semver20

SemVer 2 support (take 2)
Initial refactoring of Variable provider and the way variables are generated. Also using SemVer 2.0
Fixed bug in variable provider when there is no tag
Fixed GitHubFlow acceptance tests
Removed 'PreReleasePartTwo' and introduced a BuildMetaData class
SemanticVersionPreReleaseTag now implements IComparable
Replaced version builders with .ToString() and format options on SemVer
Removed VersionAndBranch class to clean things up
Fixed missed tests
Moved SemVer parsing into SemVer class
Improved SemanticVersion parsing
Improved SemVer tests
Fixed acceptance tests
Approved changes to classic version
Improved acceptance tests heaps
Removed unneeded approval files for acceptance tests
Starting to fix #112
Got /exec and /proj tests running again and fixed a number of command line bugs