Don't drop entire vardir on test suite start, it may have
symlinks, configuration files, etc. - useful for debugging.

1) Temporary result files weren't deleted, if test's skipcond failed.
2) Vardir is removed when tests started.
3) Sort tests and test-suites by name
4) Added cleanup to box/lua.test

* memcached/expirations.test
* memcached/flush-all.test
* replication/memcached.test

Conflicts:
	third_party/luajit

Conflicts:
	src/box/box_lua.cc
	test/box/lua.result
	third_party/luajit

Conflicts:
	.gitignore
	test/lib/test_suite.py
	test/unit/CMakeLists.txt
	third_party/luajit

Conflicts:
	third_party/luajit

Remove trailing spaces. Get rid of an unused method.

1. sleep(0.1) -> sleep(0.01)
2. _server -> serv, _replica -> _repl.

2. Refactor find_tests code
3. Rewrite and Add comment for chdir(base) (test_run.py:145)
4. Rewrite .gitignore file for new name of unit tests

Don't use palloc()/ptruncate() in box_lua.cc.
This is a pre-requisite patch for tuple-format.
tuple:transform() method remains to be fixed in a separate patch.

- make the test suite actually paste
- remove the ugly copy-paste

Use an existing method to pack a key into a tbuf.
@todo: switch to using a list of keys instead of a buffer
for expire.