Adds support for Dockerfiles, Gemfiles, Ruby files, and Groovy files.
Also, in order to fully support Dockerfile and Gemfiles, a new file
extension parser was created to deal with files that do not have an
extension.
If a license text had blank lines, they would result in a trailing
whitespace when prefixed with the line comments.
This change removes trailing whitespace from the middle lines,
leaving top and bottom as is.
Fixes#10
