fixed opPlugin:install task to check the existence of the 'sns_config' table (fixes #518)
fixed opPlugin:install task to check the existence of the 'sns_config' table (fixes #518)

ShinichiU/OpenPNE3,nishizoe/OpenPNE3,nishizoe/OpenPNE3,isaosano/OpenPNE3,openpne/OpenPNE3,C-nakajima/OpenPNE3,balibali/KakiageSNS,isaosano/OpenPNE3,isaosano/OpenPNE3,tejima/testravis,balibali/KakiageSNS,kashiwasan/symfony-advanced,upsilon/OpenPNE3,tejima/testravis,upsilon/OpenPNE3,C-nakajima/OpenPNE3,nise-nabe/ppcon-sns,ShinichiU/OpenPNE3,openpne/OpenPNE3,kashiwasan/symfony-advanced,tejima/OP3PKG,ShinichiU/AuthFramework,tejimaya/OpenPNE3,tejima/testravis,ShinichiU/OpenPNE3_with_webInstaller,tejima/OP3PKG,C-nakajima/OpenPNE3,isaosano/OpenPNE3,ShinichiU/AuthFramework,ShinichiU/OpenPNE3,openpne/OpenPNE3,openpne/OpenPNE3,ShinichiU/OpenPNE3,nise-nabe/ppcon-sns,tejimaya/OpenPNE3,upsilon/travis-test,ShinichiU/AuthFramework,ShinichiU/OpenPNE3_with_webInstaller,upsilon/travis-test,C-nakajima/OpenPNE3