Verify if jars are all signed (#1255)
Verify if jars are all signed (#1255)

* Verify if jars are all signed
* Remove tab chars / reformat code
* Check length of injected constants too
* Simplify code
* Make error messages less verbose
* Don't depend on bash features
GoogleCloudPlatform/google-cloud-eclipse,GoogleCloudPlatform/google-cloud-eclipse,GoogleCloudPlatform/google-cloud-eclipse,GoogleCloudPlatform/google-cloud-eclipse