Merge pull request #1 from psunkari/gitignore

Add ".gitignore" with build and project files.
Merge pull request #1 from google/master

Add ".gitignore" with build and project files.
Fix interpolator tests and ensure tests run successfully in content_shell. Enable continuous tests on drone.io

Ensure tests run successfully in content_shell and parse the render tree to check if any tests failed.

Fix transform interpolator.

Update build status badge.
Merge branch 'continuous_tests' of https://github.com/psunkari/charted into continuous_tests