Fixed #295. Fixed running plugin tests as group.

The regression happens because in the old revision each plugin test
had a different endpoint. Since now they (almost all of the tests)
still share the same Flask object and use the same endpoint ``/tests``,
when nosetests scans for all the test_app object, only one of the endpoint
is chosen. Sometimes if we are lucky on tearDown some are updated. But
in general, only one test file's actual endpoint is in the memory.

The solution is to pull all the Flask-related code into a separate python
file according to test. They now organized under servers/ directory.
Merge pull request #306 from yeukhon/issue#295

Fixed #295. Fixed running plugin tests as group.
Fixed #307. Run test_scan requires whitelisting localhost.

This is merely a documentation fix. If anyone intersted in
running the full test suite, or at least test_scan.py, the
runner must ensure localhost is whitelisted. This is achieved
by creating scan.json and whitelist 127.0.0.1.
Merge pull request #308 from yeukhon/issue#307

Fixed #307. Run test_scan requires whitelisting localhost.