Updated to java 8, jackson 2.x, and jersey 2.x.

[asaarela]

Updated the opsgenie Java API to java 8, jackson 2, and jersey 2. I was able to update all the submodules without issue except the 'marid' module. There were a couple of issues with this module:

• I don't have a pubnub account to test against.
• the project references an opsgenie-specific fork of the pubnub library which is not in maven central. The canonical pubnub library doesn't have the opsgenie-specific method defined. I've commented out this code for now.
• Tests dates in my timezone (EST) are causing all the data-based asserts to fail. I haven't tracked down the root cause of this.

[estsauver]

This would be great, the outdated libraries are causing us classpath conflict issues.