Close module URL stream as soon as possible

This refactors LibraryModulesSchemas.createFromURLConnection()
to close the stream before doing any further processing. This
lowers resource needs as well as makes for simpler code.

Change-Id: I08f242005185637f6dcbd37fe4ba86051624e56d
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>