add guard zeus gem.
create ticket.
edit ticket.
destroy ticket.
add ticket feature test.
add ticket require invoice and event tickets quantity.
add test for ticket destroy and update.
update ticket feature test.
remove test for mysql, sqlite and ruby 1.9.3
fix deprecates at test cases and seed
Merge pull request #452 from saberma/saberma-feature/450-create-tickets

活动管理员新增门票 #450
Merge pull request #460 from jasl/fix_deprecates

修改了过时的用法
now can use SELENIUM_BROWSER to specify which browser to use, default is firefox
Merge pull request #461 from jasl/imporve-selenium

可以选择capybara使用的浏览器