Fix Linux compilation in the Ubuntu family tree caused by Webkit changes Fixes Bug #289 and should solve Bug #299 as well, since this bug was preventing the compilation from being successful. Thanks to Odin and Smar for helping in dealing with this problem.

Change-Id: Ie9ae86ebf455b50c37acecd36ce4d97271e3a056
Reviewed-on: http://gerrit.smar.fi/343
Reviewed-by: Samu Voutilainen <smar@smar.fi>
typesystem: Reject QAccessible::Role’s Button

This is something Ubuntu and its variants adds to the enum, and
does not have any effect on any other distro.

Actual enum value is PushButton, which we will preserve, wants Ubuntu
say something about it or not.

Change-Id: Ie195b8210e6167f4865cdd5df23e9292e9c80ca7