Upgrade Maven GPG Plugin to 1.4 and Maven Deploy plugin to 2.7

Release Notes - Maven 2.x and 3.x GPG Plugin - Version 1.4

• • Bug
• [MGPG-37] - retryFailedDeploymentCount is actually just plain
  retry deployment

• • New Feature
• [MGPG-38] - gpg:sign-and-deploy Allow deployment of multiple
  side artifacts at the same time via the CLI

Release Notes - Maven 2.x and 3.x Deploy Plugin - Version 2.7

• • Bug
• [MDEPLOY-127] - Mark deploy plugin as @threadSafe for maven3
• [MDEPLOY-132] - Discrepancy between pom syntax for artifacts and
  deploy:deploy-file parameters
• [MDEPLOY-136] - retryFailedDeploymentCount is actually just
  plain retry deployment

• • Improvement
• [MDEPLOY-134] - mvn deploy:deploy-file should allow to add an
  arbitrary number of attached artifacts not only sources and javadoc

• • New Feature
• [MDEPLOY-133] - Add a configurable parameter to allow retrying deployment
• [MDEPLOY-137] - deploy:file Allow deployment of multiple side
  artifacts at the same time via the CLI