cleaned up openpne:migrate description (refs #138)
cleaned up openpne:migrate description (refs #138)

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