since this is a backward incompatible change, I set version to v2.0.0.
all symbols and functions is now prefixed with zero-input.

This change is suggested by melpa reviewer.

only run check on master branch.
pkg branch is just for zero.el distribution.

minor, update doc.

- renamed zero.el back to zero-framework.el
- to build a dist, just run "make".
  the zero.el template is in zero.el.in
- zero.el is built and added to git repo in git pre-commit hook. it will
  be kept in master branch.
- fixed a few package-lint style warning.

split ert tests to separate files. These tests are not required in melpa
distribution.

- added zero-version variable in zero-framework.el