(PUP-3013) Accept. tests - 3.7 PMT updates build

This commit adds additional acceptance test coverage for updates
the puppet module build command. These tests validate the
following:

    * enforcement of metadata.json file
    * ignoring checksum data in metadata.json
    * detection of symlinks in module
    * detection of file changes created by build process
    * use of .pmtignore and .gitignore to suppress file inclusion
      during build
    * metadata.json field validation of name
    * metadata.json field validation of semantic version
    * metadata.json field validation of version range
      incompatibility when duplicate dependencies are found