Updating LTI Jasmine tests.

Due to the fact that by default the LTI settings have "http://www.example.com"
set as the default form action (launch_url), tests were updated to reflect the
fact that when setting is in default state, form is not submited, even when
the form action is not empty.
Merge pull request #943 from edx/valera/update_lti_tests

Updating LTI Jasmine tests.