Update MeManager.java

Added new method signature to provide proxy credentials
Update MeManagerImpl.java

Added call to setProxyCredentials when proxy authentication info is provided.
Update AbstractPhoneGapBuildMojo.java

Calling createRootWebResource with proxy Username and Password when proxyInfo is not null.
Update AbstractPhoneGapBuildMojoTest.java

Changed signature for test of call to createRootWebResource when proxy is specified.
Merge pull request #15 from FredChap/master

Maven Proxy credentials settings not used