Fix bug https://bugs.launchpad.net/tarantool/+bug/988701
"Build with '-DENABLE_CLIENT=true' was broken'

Until
https://bugs.launchpad.net/tarantool/+bug/962848
"Compilation with extrnal LuaJIT broke with addition of FFI"
is fixed, don't try to compile with external LuaJIT.

Update the manual and the configuration file
to reflect the new WAL writer architecture.

https://bugs.launchpad.net/tarantool/+bug/837484

default src configuration files path changed to test/share/

'find' TreeIndex class member was fixed. Now allocate enough space for key_data.

Conflicts:
	mod/box/index.h
	mod/box/index.m
	mod/box/tree.m
	test/box/lua.result
	test/box/lua.test
	test/box_big/tarantool.cfg

As part of the merge, revers int -> u32
type change for key_cardinality, done in the
blueprint-multipart-primary-key branch (didn't
notice during code review, but it breaks
formatting in errcode.h).

Merge new and old tests in box_big
manually.