Fixes #1275. Fixes pom dynamic revision conversion

Fixes #1275

Ivy and pom uses slightly different notation for version range and dynamic revision. This change fixes the dynamic revisions involving “+”.

First, when a revision like “1.1+” is found, it will now be treated as “1.+”.
Next, when it finds a revision like “1+” is found, it will be treated as “+”. The conversion of “+” is hardcoded to be “[0,)”.

/review @havocp