[Android] Add the test case about setDatabaseEnabled

Test database by set the function setDatabaseEnabled true or false.
Then get the result by load the html which check the database
enabled or not.

This test case should add the parameter "--test_data", as follows:
build/android/run_instrumentation_tests.py --test-apk XWalkCoreTest \
--test_data xwalkview:xwalk/test/data/device_files/ \
--verbose -I --num_retries=1 -f testDatabaseEnabled
Merge pull request #560 from wuhengzhi/master

[Android] Add the test case about setDatabaseEnabled