need to turn on new patching mechanism during install runtime

Currently, we build patch msi's with the new msi redesign, but they are not yet being used for upgrade scenarios. This fix will turn them on, as well as address some other cleanup with the new msi/patch design such as:

-caching the baseimage file in a write protected location %PROGRAMDATA%\Oracle\Java\installcache, instead of locallow director that it's currently in.
-having the online installer now download the patch msi (instead of the full msi) if the baseimage is already cached on the machine
-various clean up of the installer.exe to use tstring instead of TCHAR
-new SysInfo.cpp function to retrieve/create the new installcache dir location