v0.7

Decidim 0.24 compatiblity upgrade (#62)

* initial changes

* fix version views

* fix items call

* fix appraisal

* use legacy editor for 0.23

* allow prerelease checking

* relax specs for admin checker

* rebase latests changes

* downgrade missing gem

* add codemirror to legacy admin

* fix category and operation over hashtags

* remove repeated test

* update docs