Update INSTALL.md

Taking into account absig's remarks on the ML
mapfishapp: save layer abstract to WMC
Merge branch '13.09' into 14.01

Conflicts:
	analytics/src/main/webapp/js/lib/external/ext
Merge branch '14.01' into 14.06
Merge branch '14.06'

Conflicts:
	mapfishapp/src/main/webapp/app/js/GEOR_wmc.js