add notice about compatiblity with N Preview (bug:27830549) improve linux...

add notice about compatiblity with N Preview (bug:27830549) improve linux 32-bit library information (bug:27962189), add a note about JDK 8 compatibility on Mac, and a few other edits to installation guide and system reqs. am: d69b7276 am: 1b302089
am: 663ad9cb

* commit '663ad9cb':
  add notice about compatiblity with N Preview (bug:27830549) improve linux 32-bit library information (bug:27962189), add a note about JDK 8 compatibility on Mac, and a few other edits to installation guide and system reqs.

Change-Id: Ib171b19828b3c9b985c5299668a1a22d8bb5f395