cli: Make cachemaker.py pep8 compliant

Fixes object comparision to use a "is" b instead of ==

Signed-off-by: Rohit Yadav <bhaisaab@apache.org>
INSTALL: Update INSTALL.md with newer links

- Fix Maven 3.0.5 link
- Remove references of incubating, we are TLP now :)
- Fix github mirror link and git clone url

Signed-off-by: Rohit Yadav <bhaisaab@apache.org>