Floating dialog

[jburel]

Close dialog when it loses focus
see http://trac.openmicroscopy.org.uk/ome/ticket/11698

[joshmoore]

Restarted travis since failure was:

Download error on http://pypi.python.org/simple/pytest/: [Errno 111] Connection refused -- Some packages may not be found!

/cc @ximenesuk

[mtbc]

I was interested to see what this did under XFCE4 with focus-follows-mouse but actually it is fine, the floating dialog doesn't actually lose focus so long as the mouse pointer is still within the "parent" Insight window, and then clicking outside it dismisses the dialog.

Good to merge (travis permitting).

[jburel]

--no-rebase

[jburel]

@mtbc Thanks for your tests.