allow a few more type to be shown in browser, enable pdf showing in ff
Merge remote-tracking branch 'wagn/master'

Conflicts:
	mod/wikirate/set/self/wikirate_source_preview_page.rb
check request is nil or not
support ruby <2.0
Merge pull request #88 from chuenlok/master

allow a few more type to be shown in browser, enable pdf showing in ff