Refs #6795, add --iis-map-field option to allow users of log importer script to parse log files created using the IIS Advanced Logging module. Includes tests for such a case (including python unit test + PHP System test).
Refs #4707, add test for netscaler logs, support already present due to last commit.
Refs #5980, parse cs-username variable in IIS logs and use as userid when present and not anonymous. Includes changes to ImportLogsTest.
Add netscaler logs to python tests for log importer.
Refs #6388, map IIS time-taken field to gneration time in log importer.
Merge branch 'master' into iis_advanced_log_importing

Conflicts:
	tests/PHPUnit/System/expected/test_ImportLogs__DevicesDetection.getBrowserFamilies_month.xml
	tests/PHPUnit/System/expected/test_ImportLogs__DevicesDetection.getBrowsers_month.xml
	tests/PHPUnit/System/expected/test_ImportLogs__DevicesDetection.getOsFamilies_month.xml
	tests/PHPUnit/System/expected/test_ImportLogs__UserSettings.getBrowser_month.xml
	tests/PHPUnit/System/expected/test_ImportLogs__UserSettings.getOSFamily_month.xml
Merge pull request #6825 from piwik/iis_advanced_log_importing

Added IIS advanced log importing support, netscaler log importing support, support for cs-username IIS log field and time-taken IIS log field to log importer script.