rename callback function parameter to `amber`

... in comment example at the beginning of file
Fixes #893

- Adds PackageHandler >> commitPackage:onSuccess:onError:
- Adds Environment >> commitPackage:onSuccess:onError:
- Adds PackageCommitError class
- Adds HLPackageCommitErrorHelper to help the user in case the package
- commits fails.
- Improves HLRequestWidget to also work with inputs instead of textareas
Merge branch 'master' into helios-sunit