LB-1921: Twitter search doesn't work on RP

Changed proxy to the new url https://proxy.superdesk.pro/twitter/
Squashed 'plugins/embed/' changes from 11ffffa..d866230

d866230 Merge pull request #234 from herrhorn/patch-1
18a6ad6 Merge pull request #235 from nistormihai/master
277518a LB-1916: Make sure documentation is up to date for 2.0 stable release
081678c Update CHANGES.txt for 2.0 stable release
5861f17 Merge pull request #231 from vladnicoara/manual-refresh-plugin
d49013e LB-1908 Add custom IVW code to manual refresh button on embed

git-subtree-dir: plugins/embed
git-subtree-split: d866230c24e5e3abb3c9475a08e87026fcf56042
Merge commit 'c39a06303a93815dde51c60c17e2937bad155fbb' into devel