Parses testsummary in subfolder to respect run destination.

[fonkadelic]

The *.xcresult/TestSummaries.plist file doesn't contain the the RunDestination which causes problems if the simulator OS is specified. It looks like the correct summary file is located in the subfolder *_Test/. This folder is getting parsed now.

Additional Notes:

• There is probably a problem with the destination resolver: The destination identifier is null if no simulator OS is specified. This leads to empty test results because the corresponding destination cannot be found (https://github.com/openbakery/gradle-xcodePlugin/blob/master/libxcode/src/main/groovy/org/openbakery/test/TestResultParser.groovy#L53).
• The Info.plist file in the *.xcresult bundle contains useful information which could be used for the test results generation