Ability to run a validation before pushing merge
Ability to run a validation before pushing merge

Adds a optional command for Merge to execute before pushing the merge result.

For example, `--validation 'mvn clean test-compile'`, or even more safely `--validation 'mvn clean verify'`
will make sure that the project still builds (or the tests still pass) after performing the merge and before
pushing potentially broken code to the remote.
maxzheng/workspace-tools