check/gst/gstcaps.c: Extend caps string tests to check that a caps to string conversi...

check/gst/gstcaps.c: Extend caps string tests to check that a caps to string conversion is reversible and produces th...

Original commit message from CVS:
* check/gst/gstcaps.c: (GST_START_TEST):
Extend caps string tests to check that a caps to string
conversion is reversible and produces the same caps.

* gst/gststructure.c: (gst_structure_value_get_generic_type):
Output "fraction" as the generic type fraction range, so caps
serialisation and deserialisation works.
* check/gst/capslist.h:
* gst/gstvalue.c: (gst_value_deserialize_fraction):
Support 'MIN' and 'MAX' for deserialising fractions.