Create a data structure representing a (potentially authenticated)
session.
This structure can hold authentication token.

Conflicts:
	debian/control

> remove script/ directory and move it's content to extra/

tuple.cc passed wrong parameters to small_alloc_create - prealloc
size instead of slab size, and slab size instead of prealloc size.

When correct parameters were supplied, it turned out that
objsize_max is calculated wrongly, and the last factor pool
in small allocator is too framgented (uses 3 empty slots instead
of 4, with 25% overhead).

The problem would not show up in any test, only increase
memory fragmentation.

This patch also fixes this problem.

Conflicts:
	test/box/fiber.result
	test/box/fiber.test

Conflicts:
	doc/user/connectors.xml
	doc/user/language-reference.xml
	doc/user/stored-procedures.xml

Conflicts:
	CMakeLists.txt
	client/tarantool/query.c
	client/tarantool/tc.c
	client/tarantool/tc_cli.c