Merge pull request #46 from Nerdwin15/develop

Updated README release notes
Set version to 2.2.1-SNAPSHOT
Update IsMergeableFilter to ignore PullRequests that are not OPEN

Issue #47
Merge pull request #48 from Nerdwin15/PReventFix

PullRequest eevent fix
Set pom to 2.2.1 and update README