Include Fossil-SCM support

[bohwaz]

This patch brings Fossil-SCM support.

Some of the meta_data_directory code has been changed as Fossil checkout metadata file can be named either FOSSIL or .fslckout.

[bradsokol]

Thanks for the PR.

For some time now I have not been using Sublime or Mercurial, the main reasons that I made VcsGutter. I have not had the time or resources to properly support the package. For this reason, I am hesitant to take on support for a new VCS - especially one with which I am not familiar - if I won't be able to commit the time to properly support it.

While I appreciate the effort you put in to this PR, and supporting VcsGutter, I'm reluctant to take on support for a new VCS since I have limited time to give to VcsGutter.

[bohwaz]

hey, I understand but I can commit to support Fossil in VcsGutter, or if you don't want to merge I'll fork the project and maintain a fork, either way.

But anyway, there shouldn't be need to support anything, it's not like it was a big project, this is just a few lines of code, and VCS don't change every morning ;)