* Set execute bit on files if and only if they begin with (#!).
Git only tracks the 'x' (executable) bit on each file. Prior to this
CL, our files were a random mix of executable and non-executable.
This change imposes some order by making files executable if and only
if they have shebang (#!) lines at the beginning.
We don't have any executable binaries checked into the repo, so
we shouldn't need to worry about that case.
* Added fix_permissions.sh script to set +x iff a file begins with (#!).
* Add ruby 2.6 test
* Fix broken tests
* Fix compatibility test
* Fix bundler version
* Use new docker image
* Fix broken test
* Use new docker image in ruby26 test
* Install ruby for mac
* Add continuous test for ruby 2.3, 2.4 and 2.5
* Change ruby 2.5 to 2.5.0
* No need to provide argument to rb_funcall when argc is 0
* Fix tests for ruby 2.5
* Use rescue instead of assert_raise to accept subclass of error
