Theme fixes

[jreidinger]

Draft of layout changes in registration dialog in installation. Several possible changes are shown. Basically each option represent evolution done by each commit.

Vertical Spacing Only

The first commit is just remove of vertical spacing:
qt:

ncurses:

Left Align

The second try to remove center align and instead align to left:
qt:

ncurses:

and minimal ncurses

Left Align and Margin Box

The third try includes left align and margin box around

Left Align and Horizontal Stretch

The forth try uses HStretch instead of Margin Box.

Left Align and Horizontal Stretch and Network Button separate

It is same as previous one, just network button is moved to right edge. Looks like there is agreement that this layout is the best one from proposed.

[jreidinger]

@kwwii Can you check screenshots here what you prefer? On the second set I can also try to define instead min size for input fields and remove it horizontal stretching, so it can be shorter in qt and also ncurses.

[coveralls]

Coverage decreased (-0.3%) to 84.034% when pulling 6470464 on theme_fixes into 832dc62 on master.

[jreidinger]

One more screenshot for default center aligned registration with high resolution which result in different view ( just part attached )

[mvidner]

For testing of big-resolution layouts it may be helpful to scale down the qemu display so that it still fits your physical screen:

man qemu-kvm:

       During the graphical emulation, you can use special key combinations to
       change modes. The default key mappings are shown below, but if you use
       "-alt-grab" then the modifier is Ctrl-Alt-Shift (instead of Ctrl-Alt)
       and if you use "-ctrl-grab" then the modifier is the right Ctrl key
       (instead of Ctrl-Alt):

       Ctrl-Alt-f
           Toggle full screen

       Ctrl-Alt-+
           Enlarge the screen

       Ctrl-Alt--
           Shrink the screen

       Ctrl-Alt-u
           Restore the screen's un-scaled dimensions