Add support for gpg.
Add support for gpg.

marcusholl/xcode-maven-plugin,hohteri/xcode-maven-plugin,sreedhargs89/xcode-maven-plugin,marcusholl/xcode-maven-plugin,hohteri/xcode-maven-plugin,sreedhargs89/xcode-maven-plugin,sreedhargs89/xcode-maven-plugin,sreedhargs89/xcode-maven-plugin,marcusholl/xcode-maven-plugin,hohteri/xcode-maven-plugin,hohteri/xcode-maven-plugin,marcusholl/xcode-maven-plugin