DS Wizard: Fix alignment of the 'Lifecycle Methods' drop down

The primary purpose of this patch is to fix the alignment of the
'Lifecycle Methods' field in the New DS Wizard, but it also:

* Externalizes a handful of the strings in the wizard and wizard page
* Wraps the ActivateSignature enum declaration
* Changes the wizard's dialog title from "New Java Class" to "New
Declarative Services Component Class"

Here is a before and after:
![image](https://cloud.githubusercontent.com/assets/114601/3999274/27c962ee-294f-11e4-9adb-1a21294f945c.png)

Ignore the different window icons, that is just an artifact of running eclipse through the eclipse run profile without using its native launcher.