Message changed for course import when timeout.
STUD-1283
Merge pull request #3232 from edx/waheed/stud1283-added-message-when-timeout-on-import

Warning message changed for course import when timeout.
Remove params from list.
Tweaking automatic screenshots in acceptance tests.
Merge pull request #3277 from edx/oleg/custom-params-fix

Do not allow user overwrite some LTI parameters using custom parameters field. BLD-989.
Merge pull request #3273 from edx/valera/hendrixx

Tweaking automatic screenshots in acceptance tests.
Work.
Update numbering of acceptance tests.
Fixing test.

Only 00:00:10 needs to be passed. It will be converted by xfields::from_json
method.
Removed unnecessary screenshot captures.
Removed unnecessary import.
Adding more tests.