planex: Import xenserver-core's Spec wrapper class

Signed-off-by: Euan Harris <euan.harris@citrix.com>
configure: Remove dependency on spectool

We can now use the Spec class's source_urls() to get the source URLs.
Spawning spectool to parse the Spec file is no longer required.

Signed-off-by: Euan Harris <euan.harris@citrix.com>
test_planex_spec: Test all forms of source URL

Signed-off-by: Euan Harris <euan.harris@citrix.com>
spec: Report sources in the order they are defined in the spec file

Signed-off-by: Euan Harris <euan.harris@citrix.com>
Merge pull request #34 from euanh/planexsc

Import specfile-handling class from xenserver-core