WCS 1x timePosition handling without a second DescribeCoverage request

[roomthily]

Current GetCapabilities parsing ignores the timePosition extent element in favor of a DescribeCoverage request. We still want to extract as much as possible from a local file copy so this is not the preferred behavior.

Note: the DescribeCoverage request may not be functional anyway (or may be inconsistent or have version assumptions, etc).

[roomthily]

And extend to capture multiple time position or dimension.