[Android] Implement cookie manager for runtime.

1. Persitent cookies with disk cookie store rather than memory.
2. Enable cookie access policy for network.
3. Implement Java interface to get, set, remove and allow cookies.

Bug=https://crosswalk-project.org/jira/browse/XWALK-156
[Android] Add core case for cookie manager.
This test covers the basic features of cookies, including:
1. AcceptFileSchemeCookies
2. AcceptCookie
3. RemoveAllCookies
4. CookieExpiration

Steps for test:
1. install XWalkCoreShell.apk
2. python build/android/test_runner.py instrumentation \
--release --test-apk=XWalkCoreTest --test_data \
xwalkview:xwalk/test/data/device_files/  --verbose \
-f CookieManagerTest