[BUGFIX] Packages can be frozen in Development only
Freezing packages was not possible in other contexts than Development
with the related commands. But if a package was frozen according to
PackageStates.php, it would advertise itself as frozen in all contexts.
While this did not seem to have any real effects, it caused confusing
output with the cache:flush command in Production context.
This change makes the Package class ignore the frozen state in any
context except Development and adds a check in the freezePackage()
method of the PackageManager.
Releases: 1.1, 1.2