Rename travis_test.sh to test_travis.sh

It was breaking ./bin/t<TAB> -> ./bin/test and it was driving me nuts.
Make test_travis.sh not executable
Add tests for issue #3626
Try to predict a correct number of taylor terms for function expansions with non-atomic argument, e.g. sin(sqrt(x)).series(x)
Fix test_code_quality.py failure: trailing whitespace in polytools.py
Merge branch 'master' into 3626
log(Product(...)) -> Sum(log(...))
Revert "Make test_travis.sh not executable"

This reverts commit 85886937514ae3d3f5105f45542d6d717ae03ee8.

Travis doesn't work if it isn't executable.
log(Product) -> Sum(log) requires simplify
log(Product(arg)) simplifies if arg.f.is_positive
Merge pull request #1774 from asmeurer/travis_test

Rename travis_test.sh to test_travis.sh
Merge pull request #1816 from skirpichev/3626

Fix for #3626

Function._eval_series() does wrong prediction for number of taylor
terms if the argument of function is non-atomic.
Merge pull request #1822 from mrocklin/log-product

log(Product(...)) -> Sum(log(...))
Merge branch 'master' into 3669-rsolve_hyper