Don't force push to sympy_doc
Deploy the docs as part of the script phase in Travis

This has several advantages:

- If it fails, the build will fail.
- We do not need to rebuild the docs. They are already built from the test
that builds the docs.
- We do not arbitrarily only deploy when the first test in the matrix is
finished. The deploying is now tied to the docs building matrix.
Fix bash syntax in .travis.yml
Fix name of deploy script in .travis.yml
reposition Leonid Blouvshtein in AUTHORS/aboutus
Merge pull request #8214 from asmeurer/travis-docs

Travis docs
Add _eval_Eq methods for Interval, ProductSet and FiniteSet
Don't make clean after building the html docs in Travis

We need to keep the docs around so that they can be deployed.
Merge branch 'master' of git://github.com/sympy/sympy
Improve FiniteSet._contains

fixes #8197
fixes #8209
More debug messages in deploy_doc.sh
Merge pull request #8226 from skirpichev/8197-fix

Improve FiniteSet._contains
Correct docstring of Pow for 0**negative; few formatting fixes
Add Pow._eval_is_zero() helper

fixes #7965
Fix Pow._eval_is_negative (if base>=0) and tests:

the problem is: if k>=0 - for k**-2 we can't say anything
definite (i.e. it's positive), because 0**-2 is zoo.