Fix #198: Names like '' and 'x.y' and 5 and 'primary ' are legal
Add locale-aware check to identifier_is_valid
Set LC_CTYPE to en_US.UTF-8 (a request from anglophile lobby)
Introduce ER_IDENTIFIER for errors related to incorrect object names.
Merge branch 'gh-198-invalid-identifiers'

Conflicts:
	test/box/misc.result
Merge branch 'master' of https://github.com/tarantool/tarantool