Upgrade to Gradle 1.6 and resolve deprecations

This patch upgrades Gradle to 1.6 and resolves related deprecation
warnings.

Issue: GAP-144
Merge pull request #2 from sslavic/GAP-144

Upgrade to Gradle 1.6 and resolve deprecations
Merge pull request #3 from aldaris/master

BuildInfoRecorder can upload "stale" POM when using maven-shade plugin
'build-info-extractor-maven3-plugin' added
ExtractorMojo - correct build timestamp is used.
ExtractorMojo - better check of whether the plugin was invoked already (artifact resolvers are also checked).
Merge pull request #4 from evgeny-goldin/master

Maven plugin added
ExtractorMojo - "deployProperties" support.
ExtractorMojo - resolver, publisher, buildInfo fields added + PropertiesHelper.
ExtractorMojo - licenses, issues, blackDuck properties.
Merge pull request #5 from evgeny-goldin/master

Deploy properties + new config containers
ExtractorMojo - handler settings are printed when Maven is run with "-X" flag.
ExtractorMojo - "artifactory" handler added + DelegatesToPrefixPropertyHandler interface.
Merge pull request #6 from evgeny-goldin/master

Handler's settings are dumped when Maven is run with "-X" flag
ExtractorMojo - prints all <configuration> values.
ExtractorMojo - old properties are eliminated + code cleanup.
ExtractorMojoHelper - supports "{EXPR}" and "{A|B|C}" expressions when values are replaced with env. variables or system properties.
ArtifactoryClientConfiguration.java + ClientConfigurationFields.java - changes reverted
ExtractorMojoProperties + @Property removed
ExtractorMojoHelper cosmetics.