Fix indentation.
Adds configurable gerrit baseUrl.

Not all gerrit installations are configured to listen to:
  listenUrl = proxy-http://localhost:8080/

If you have it configured to listen to:
  listenUrl = proxy-http://localhost:8080/gerrit

Then all the REST calls will fail because they follow the form:
  GET /a/...

This change adds the variable BASE_URL that can be configured in:
  Jenkins -> Manage Jenkins -> Additional properties: "(...) -DBASE_URL=gerrit"

So the REST calls will have the form:
  GET /gerrit/a/...
Improve baseUrl implementation.

It cleans up some of the parts of the implementation to make it more consistent.
The biggest change is that the GerritConfiguration now cleans up the baseUrl to
make it URL compatible at all times.
Merge pull request #4 from gjorquera/configurableBaseUrl

Configurable base url