KSENROLL-14743 Add ListOpenPullRequestsMojo

This mojo will look at the list of open pull request's and then write a file,
open-pull-requests.dat, into the current working directory of where the plugin
is being run that contains data on the pull request and commit that should be
tested next.

The output format is: pull request number [colon] commit object id
KSENROLL-14743 Add .gitattributes file