Update in the manifest version number generator

Hi

Sorry to bother you, but I ran in to an issue with the performVersionCodeUpdateFromVersion(Element) method. I need it to work with version numbers like 2.1.5.0-SNAPSHOT so I created a fork.

I updated the manifest version number generator. Now for every number in the manifest version name, a three digit representation is added in the version code. 

Examples: 
1.01-SNAPSHOT -> 1001, 
2.1.5.0-SNAPSHOT -> 2001005000, 
2.0-SNAPSHOT -> 2000

I'm not sure if this is acceptable for you, but just in case I created a pull request so you can check it out.

Regards,
Zlatko