Add use_maven_local property

If set to true in gradle.properties, artifacts in the local Maven repository will be used instead of downloading them. The expected workflow is to set this and override version_proteus in gradle.properties to the development version (e.g. 0.7.0 as of this writing), then build Proteus using ```./gradlew install``` to install it in the local repo. You can then build your application using ```./gradlew war``` and deploy it.

https://docs.google.com/a/vipasolutions.com/document/d/1Y4Xfn_d3XyrgyXscVDcwcbGRXMPcSN2xyOmfneUAttg/edit