Improve wording and tense in some "page language" strings

Improve wording and tense in some "page language" strings

The titles of "action" special pages are normally expressed as actions
("Move page", "Reset password", "Upload file"), and the names of
log types are normally nouns ("Deletion log", "Content model change log").

In any case, "Change language log" and "$1 changed page language for $3"
are not good English.

Log entries also do not end in full stops.

Change-Id: I1d2fed64549ce584418bb3b72d33bf5657c2681f