Add proposals for ajax.event

[bvfalcon]

Show possible values as proposals for attribute event of tag ajax:

<h:commandButton id="button">
  <f:ajax event="<HERE>" />
</h:commandButton>

[nitind]

@bvfalcon Could you make an addition of the EPL 2 license header to these new classes, with the copyright assigned to yourself, or your employer, depending on your hiring agreement?

[nitind]

@bvfalcon I shouldn't merge these unless the license is properly applied to those new files.