Refactor tests and cosmetic changes in bogo/new_bogo_engine.py

Signed-off-by: Trung Ngo <ndtrung4419@gmail.com>
Refactor remove_mark_char()
Refactor valid_vietnamese.py, mostly cosmetic

- Cut long list into shorter lines
- PEP8
- Add STRIPPED_VOWELS (uo, uye,...) and only check vowel in there
  if not checking final_form
- Allow 'êc' (giếc - doesn't seem to have any meaning at all, but it's
  in the dictionary anyway).
Fix not importing logging module in config.py
raw_string -> raw_key_sequence in new_bogo_engine.py
New test facility based on `nosetests`

Now we can run tests by running `nosetests` in the main directory.
Add CONTRIBUTE.md and INSTALL.md from wiki

And remove the wiki all together. Maintaining local docs, wiki and
the website is too much.
Fix "này" + "." -> "naỳ."
Handle "uơ" in "huơ", "thuở", "quở"

If the current word has no last consonant and the first consonant
is one of "h", "th" and the vowel is "ươ" then change the vowel into
"uơ", keeping case and accent. If an alphabet character is then added
into the word then change back to "ươ".

NOTE: In the dictionary, these are the only words having this strange
vowel so we don't need to worry about other cases.
PEP8 in new_bogo_engine.py and more test cases