[MAT-476] Add slf4j version to pom.xml.

Adds a concrete version of slf4j to the pom.xml.
[MAT-476] Add maven deploy test command.

This adds the maven_test_deploy target to cmake. The purpose of
this is to enable automated testing to ensure the pom.xml is
valid and parsable.
Merge pull request #136 from OpenGamma/MAT-476

Mat 476 adding deploy target