Fix UI messages
Implement CSP postprocessor (mainly to cope with CSP issues in Polymer JS)
Merge remote-tracking branch 'upstream/master' into csp-fixer
Switch downloading mechanism for bower packages: git clone -> zipped archive
Factor out an XHR-downloading function
Comments
Merge remote-tracking branch 'origin/download-bower-pkgs-as-zips-2' into csp-fixer
Merge remote-tracking branch 'upstream/master' into csp-fixer
Remove unused import
First working CSP postprocessor (with known problems)

Known problems:
- Doesn't get started after an initial project creation or a 'bower install/update' run on a directory with no bower_components.
- Doesn't analyze the type of a script being outlined; that should at a minimum determine the extension.
Mostly comments
Numerous further fixes and additions
Remove CSP fixing from Bower process and add an explicit context action/job
Merge remote-tracking branch 'upstream/master' into csp-fixer
Merge remote-tracking branch 'origin/csp-fixer' into csp-fixer

Conflicts:
	ide/app/lib/package_mgmt/bower_fetcher.dart
Revert a comment
Review comments #1: missing type
Review comments #2: print success/failure message when CSP refactoring is done
Merge pull request #3067 from ussuri/csp-fixer

Introducing the CSP Fixer