Tests for AuthenticationHttp and AuthenticationSignon
UTs for libraries/plugins/Plugin*
UTs for libraries/properties/*
added methods PMA_executeQueryAndSendResponse, PMA_sendResponse
phpcs errors and warnings corrected
use $GLOBALS['cfg'] instead of parsing $cfg variable among methods
renamed methods to better reflect their usage.
changed comments to better reflect the origin of the parameter $selected
error corrected
phpcs errors and warnings corrected
Fix merge conflicts
Fix typos
Merge pull request #513 from ayushchd/unit_testing

UTs for libraries/plugins/auth*, libraries/properties/*, libraries/plugins/Plugin*
Merge branch 'master' of https://github.com/phpmyadmin/phpmyadmin into UT_plu_parse