[model] util: Add new DateTimeConverter helper

Convert from org.joda.time.DateTime attribute to
java.sql.Timestamp
[jpa] add orm.xml with converter specs for DateTimeConverter
[model] Conference: +{start, end, deadline, logo, thumbnail }

Add new fields to conference
[service] Conference: order list/listOwn by startDate
minimal conference info page
added sign up and sign in buttons
Merge pull request #76 from gicmo/ConferenceModelChanges

Conference: +{start, end, deadline, logo, thumbnail } fields
Merge pull request #75 from asobolev/master

Moved RESTResults to GCAAuth for compliance

OK
models.js: add position to models
editor: some improvements
editor: author and affiliation editor working
editor: display affiliations correctly
editor: adjust modal window layout

cleanup styles
layout.less: default content for empty editor parts
Merge pull request #77 from stoewer/master

Further improved editor

LGTM
smallest version of the conference page
Merge branch 'andrey'