Fix URL resolver so that we can push Maven artifacts to local maven repositories.

* Hook "LocalIfFile" repository to also handle publishing
* Add test to ensure mavne publishign works.
Add workaround (and warning message) for when ChainResolver gets a null publication date while we investigate other issues.

* Attempt to set publication date to last modified time, if the stars align
* Issue warning about undefined resolution behavior otherwise
* Add scripted test which exercises the NPE issue in resolving -SNAPSHOTs.
* Commit scalariform style edit in Act.scala

* After parsing and transforming the pom, check for pub date.
* If we don't have a pub date, try to grab lastModified from the URL
* If we can't do anything, issue a warning about the problem artifact.
Adding notes for ChainResolver fixes.

Fixes #1611
Fix NPE in ChainrResolver when there is no ivy file for a dependency.
Merge pull request #1618 from sbt/wip/mavne-resolution-woes

Fix various issues with maven + Ivy