Some minor organization improvements:

1) Greate journey of files:
	* `\src\tarantool` -> `\tarantool`
	* `\tests\tarantool` -> `\tests\suites`
2) Temporary schema test moved to core tests and was rewritten using unittest
3) Test search was moved to loader.discovery() method
4) Some documentation refactoring
5) Path fixes, chdir to main dir in the beggining of `setup.py`