Merge pull request #35 from andrmuel/master

check if conference exists on signup page
pentabarf import updated

* more documentation on importing from pentabarf
* improved event rating import speed
* carefully import long links
* fix user role import
* redirect deleted users
* respect conference timezone on event import
* sorted Gemfile
Add a feedback tab to the person page. Add stddev value to average
feedback. Hide buttons in cfp interface if conference is in the past.
clean readme
import/export conferences
cfp interface, redirect for #show action
fix for daylight saving with timezone in pentabarf import
fix event rating in pentabarf import
use raty to show stars for all ratings/feedbacks
handle pentbarf booleans (t/f)
guard against nil days
allow reviewers to read other Person objects
redirect to :back instead of login screen if an ability is missing
show conference acronym for events that do not belong into the current
conference. This applies to the person page and the event information
page.
pentabarf import: use the event state instead of his progress while
importing (why did i break this?)
pentabarf import: live system handles times differently?
forked all dependencies into our github group
pentabarf import: import ratings when running rake pentabarf:import:all
frab_export_import: export all paperclip files and re-import them
disable rails XML parameters in http requests