Fixed most PHPCS errors in User.class
Renamed md5_salt and md5_unsalt to be camelcase
Ran User class through PHPCS
Fixed syntax error in User class
Fixed errors in User.class.inc
Replaced Utility function unparse_str with PHP builtin

The built in PHP function http_build_query does the exact
same thing as the Utility function unparse_str, but is less
ambiguously named (and doesn't cause PHP_Codesniffer to complain).
This updates the references to use http_build_query.
Merge pull request #820 from driusan/PHPCS-User

Phpcs user