update captcha

html/exhi/application/controllers/General.php

html/exhi/application/models/company/M_company.php

html/exhi/application/models/general/M_general.php

html/exhi/application/models/instructor/M_instructor.php

html/exhi/application/models/project/M_project.php

html/exhi/application/models/tag/M_tag.php

html/exhi/application/models/user/M_user.php

html/exhi/application/views/general/v_general_select.php