Properly handle glob patterns and corresponding WPS apps

[fmigneault]

When a CWL output glob pattern (ex: glob: "*.nc") is employed, the output of the WPS app should automatically define maxOccurs="unbounded", or any overriding maxOccurs value specified in the Deploy body.

Also, this output should be considered as an array (list), so that wps_package collects multiple files/data here:

weaver/weaver/processes/wps_package.py

Lines 1561 to 1592 in cb17e37

	def make_outputs(self, cwl_result):
	# type: (CWL_Results) -> None
	"""
	Maps `CWL` result outputs to corresponding `WPS` outputs.
	"""
	for output_id in self.request.outputs: # iterate over original WPS outputs, extra such as logs are dropped
	# TODO: adjust output for glob patterns (https://github.com/crim-ca/weaver/issues/24)
	if isinstance(cwl_result[output_id], list) and not isinstance(self.response.outputs[output_id], list):
	if len(cwl_result[output_id]) > 1:
	self.logger.warning(
	"Dropping additional output values (%s total), only 1 supported per identifier.",
	len(cwl_result[output_id])
	)
	# provide more details than poorly descriptive IndexError
	if not len(cwl_result[output_id]):
	raise PackageExecutionError(
	"Process output '{}' expects at least one value but none was found. "
	"Possible incorrect glob pattern definition in CWL Application Package.".format(output_id)
	)
	cwl_result[output_id] = cwl_result[output_id][0] # expect only one output
	if "location" not in cwl_result[output_id] and os.path.isfile(str(cwl_result[output_id])):
	raise PackageTypeError("Process output '{}' defines CWL type other than 'File'. ".format(output_id) +
	"Application output results must use 'File' type to return file references.")
	if "location" in cwl_result[output_id]:
	self.make_location_output(cwl_result, output_id)
	continue
	# data output
	self.response.outputs[output_id].data = cwl_result[output_id]
	self.response.outputs[output_id].as_reference = False
	self.logger.info("Resolved WPS output [%s] as literal data", output_id)

We could explore the use of a builtin app array2single for cases where glob is used to collect an expected unique output.

When an unique file glob pattern is used (ex: glob: "output.nc"), then the process should automatically define maxOccurs=1 and the wps_package output should resolve any CWL glob list (as required) to an unique reference.

Furthermore, the specific extension could be employed to automatically set mediaType if not provided with more specific values.

Relates to #25

[fmigneault]

Regardless of glob pattern, multiple items should instead be detected via the File[] or type: array, item: File notation.
A generic * glob could still be used to collect a single File (just that any name is valid), such as a randomly generated file name.