(bug 36819) Lowercase be,csb,cu,dsb,hsb,rue,sgs,szl

(bug 36819) Lowercase be,csb,cu,dsb,hsb,rue,sgs,szl

Follow up to gerrit change 7306:

https://gerrit.wikimedia.org/r/#/c/7306/

Lowercase some Central and Eastern European language
names (mostly Slavic and Samogitian, using lithuanian
rule).

	'be-tarask' => "беларуская (тарашкевіца)",	# Belarusian in Taraskievica orthography
	  (as well as be-x-old)
	'csb' => 'kaszëbsczi',	# Cassubian
	'cu' => 'словѣ́ньскъ / ⰔⰎⰑⰂⰡⰐⰠⰔⰍⰟ',	# Old Church Slavonic (ancient language)
	'dsb' => 'dolnoserbski', # Lower Sorbian
	'hsb' => 'hornjoserbsce',	# Upper Sorbian
	'rue' => 'русиньскый',	# Rusyn
	'sgs' => 'žemaitėška', # Samogitian
	'szl' => 'ślůnski',	# Silesian

Change-Id: Ic0420299c9010f62d2a8fbfd6cb1d65c6b4b8413