MOSYNC-3131. Changed the url used in ParallelDownloader test app.
MOSYNC-3131. Fixed mutex used for CRITICAL_SECTION.
Merge pull request #489 from mvasiliniuc/ThreeThreeOne_CircularFifoFix

MOSYNC-3131 ParallelDownloader is unstable on iOS
Merge remote-tracking branch 'github_origin/ThreeThreeOne' into github_sandbox_threethreeone