OS X: Add system requirement OS X 10.7 to Info.plist

Since 10.6 is no longer supported (C++11).
With the explicit system requirement, the user gets a nice message
about minimum system requirements, instead of a comment-less crash at
startup.

Change-Id: I909796ce8c5a303162b7a778311b95ed06a28108
Reviewed-by: Jake Petroules <jake.petroules@petroules.com>
BinEditor remove m_widget member

As it is stored in IContext, done similar to BaseTextEditor

Change-Id: I858c75f38d55edf9b13e9c04ca2ff1586e06670e
Reviewed-by: hjk <hjk121@nokiamail.com>