fix 116: vote api will return null for image url if it's missing

also added a test to see that a vote with an agenda is returned without
error
Merge pull request #118 from yoniYalovitsky/ISSUE-116

Closes #116: vote api will return null for image url if it's missing
Remove indiegogo from home page
translations and strings fixes
Merge branch 'master' of github.com:hasadna/Open-Knesset
disable creating new tags by users
Show only current parties in agendas index
Merge branch 'master' of https://github.com/ofri/Open-Knesset
added links to committee names on committees a mk is on at mk_detail.html template