Allow managed only code which is commented in unmanaged deployments

Fixes #95 

deployCIPackageOrg now strips the string `//cumulusci-managed` from any classes or triggers before calling deployWithoutTest.  For example, `//cumulusci-managed@deprecated` gets changed to `@deprecated` when deploying to the packaging org.

- Added new macro stripManagedToken
- Added createManagedSrc and revertManagedSrc targets
- Call createManagedSrc and revertManagedSrc from deployCIPackageOrg

@almostthor could you test out this branch and see if this works for you?