GeoGebraCASIntegrationTest:

Added further test cases for ticket #2910,
added test case for solve,
added test case for a ticket that does not exist.

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@28015 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e