added ru translation
more translatable strings
ru translations for new translatable strings in templates
forgotten i18n templatetags loading
updated ru translation
translation for form fields
use GCBV for delete event view
fix error in daily view when USE_TZ=False
completely remove django's timezone warnings from tests
fix error in event when comparing dates when USE_TZ=False
translatable string for dialogs
restored accidentally deleted test, check for next context variable existing in delete view
using include tag for inserting detail info about occurrence in template

with this method we can use all of the parent context variables in included template
fix comparing Occurrence with object of other types
possibility to create Occurrence model with all empty fields
Merge pull request #28 from GeyseR/master

Comulative fixes and improvements