[Improvement] - The installer window should have a minimum size

[FMog]

As in title.

See GAT report:

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12.05.2015 20:30 GMT
Windows 8.1 Pro x64
Affected items: Windows
Priority: Usability

ACTUAL RESULTS:-
Users will notice that the installer window can be shrunk down to just a portion of the title bar. There is no point to allow the user to shrink the window until no elements from the original window are visible

EXPECTED RESULTS:
A minimum windows size should be defined, preferably one that allows for some, if not all, of the UI elements to be visible

OTHER NOTES / ERROR MESSAGES:-
http://bugs8.gatserver.com/uploads/8b1b0692f2871eb4d8afe229ff7f24c5.mp4

Steps to reproduce this issue
1.Launch the installer
2.Shrink the window as much as possible
3.Notice that the window shrinks until no UI elements are visible, just a portion of the title bar

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https://github.com/KanoComputing/GlobalAppTesting/issues/192