Removed useless files from external packages like demo.html, README.md etc.

This will reduce the number of files in the deployed app and help with the Windows installation issue.
Updated changelog.md
More updates to changelog.md
Better description of Stagehand
Removed a yet-unavailable feature
Further release notes clarifications
Release notes
Separated SparkUiAccess into Ui and Dom classes (to remove possible circular references).  Added mousedown and mouseup to ClickElement handler to fix test case.  Separated onTransitionComplete handler from actual transition event.  Fixed 3 tests and removed disabling of a fourth one (so that it tests locally as we as headless).  Added flag to getProjectLocation so that we can forego the project dialog if no root has been selected.
Merge pull request #3656 from ussuri/remove-useless-external-files

Removed useless files from external packages like demo.html, README.md etc.
Merge branch 'master' of https://github.com/dart-lang/chromedeveditor into umop-fix-ui_tests
Release note
add LG optimus v3 to usb device list
Merge pull request #3659 from sunglim/lgphone

add LG optimus v3 to usb device list
update the paper grind script
delete .bower.json
more files
Increase time delay in reading flags due to race condition.
Re-enable build for daritum.
Merge pull request #3663 from dart-lang/fix_build_for_dartium

Fix build for dartium
Add git status command.