Refs #8787 Progress bar implemented.

Progress bar is now attached to the status bar

The problem I encountered was that the Mantid window brings itself tot he front when processing occurs. So you've actually got to move the gui away from the mantid main window to see this working
Merge remote-tracking branch 'origin/feature/8709_loadIDF'
Merge remote-tracking branch 'origin/bugfix/8793_convfit_plotting'
Merge remote-tracking branch 'origin/feature/8587_DOS_port'
Merge remote-tracking branch 'origin/bugfix/8753_back_syntax'
Merge remote-tracking branch 'origin/feature/8392_bayes_add_sample_logs'
Refs #8787 Merge branch origin into 'feature/8787'

Conflicts:
	Code/Mantid/scripts/Interface/ui/reflectometer/refl_gui.py
Merge branch 'feature/8787_Refl_gui_progressbar' into develop