Bumped Brackets to Sprint 35

* Added `encoding="utf-8"` to the XML declaration
* Adapted package version to official version (0.35), because Brackets reports itself as 0.35, also in the Windows registry and in the Linux packages.
* Used the `Start-ChocolateyProcessAsAdmin` helper for the uninstall routine, otherwise the script would terminate **before** the uninstallation is complete, which is bad for batch processes.
* Better package icon

In addition I have a suggestion: The release cycles of Brackets are very short, which makes it a time-consuming task to manually keep this package up to date.
If you would make me a co-maintainer of this package, I could make an [automatic package](https://github.com/chocolatey/chocolatey/wiki/AutomaticPackages) out of it. I’m already a maintainer of [over 100 automatic packages](http://chocolatey.org/profiles/purity) ([my GitHub repo](https://github.com/TomOne/chocolateyautomaticpackages)). I would really appreciate it if also the Brackets package would get quick updates.

Btw.: My username on chocolatey.org is purity.