Check user participation in events. Closes #123
Add tests for datetimehelper
Add js file uploader for texarea
Change file uploader
Add interface for file upload
Merge remote-tracking branch 'origin/master' into upload
[WIP] Add sign for uploaded files
Fix word wrap in messages
Fix empty message displaying if there was error in message sending
Fix file block color in fineuploader
[WIP] Implement uploading files to the conversations. See #112
Merge remote-tracking branch 'origin/master' into upload

Conflicts:
	public/js/pjax/pjax-navigation.js
[WIP] Add loading.gif for file uploads. Add new line for images
[WIP] Replace attachments in conversation list page
Fix mime check. Closes #112