Exposing validate for general use

[grtjn]

You can verify if a cluster config matches your config by running the undocumented ./ml {env} validate_install. I think it is useful to expose it to public as a validate command. We do need to catch the error, and return a message alike bootstrap. Small change..

[grtjn]

Output would look like this:

$ ./ml local validate
Validating your project installation into MarkLogic on vgtest-v7-ml1...
ERROR: Missing role: test-role (VALIDATION-FAIL):
See MarkLogic Server error log for more details.
... Validation ERROR
$ ./ml local bootstrap
Bootstrapping your project into MarkLogic 7 on vgtest-v7-ml1...
... Bootstrap Complete
$ ./ml local validate
Validating your project installation into MarkLogic on vgtest-v7-ml1...
... Validation SUCCESS

A response with the full list of differences would also be nice, but this would be at least a start..

[grtjn]

Fixed in dev