Added content.
Merge branch 'master' of https://github.com/apalsapure/appacitive-dev-center

* 'master' of https://github.com/apalsapure/appacitive-dev-center: (41 commits)
  made some changes in todoapp tutorial for javascript
  updated readme
  fixed 404 pages on sdk download page. fixed height issue for smaller resolutions
  added promises section in getting started for javascript
  Updated downloads page.
  added error sc=oace for android
  Fixed issues in iOS guides
  added download url
  added cdn urls and sdk conventions
  added screenshots to dev centre
  added some connection docs
  completed query docs
  added data store docs
  updated the todo app
  Fixed the topic headings in DataStore guides.
  Fixed image size issue and added guide for debugging.
  Added guide for error space.
  Added iOS guides
  added sdk conventions for javascript sdk
  data store docs
  ...
Added guides for access control
Merge branch 'master' of https://github.com/apalsapure/appacitive-dev-center

* 'master' of https://github.com/apalsapure/appacitive-dev-center:
  added blank project link in getting-started for javascript
  changed video and template url for javascript todo sample