Add PDF building

This commit add PDF building tox.ini environment and options for LaTeX
output. overview.rst is copied from README.rst. And, the original
README.rst file is shrunk because we don't need such a long information
in the README file. People can see the same contents in overview.rst
now.

Change-Id: Id654c814988e78704726d2ba8bea9a03ce8596f8
7 files changed