Added arm64 support
Only build arm64 if 7.0 SDK is present
Updated libetpan url back to Hoa's master
Merge pull request #401 from mronge/arm64

Added arm64 support.
Fixed #378: Added INBOX when there's a non-empty prefix
Revert "Only build arm64 if 7.0 SDK is present"

This reverts commit d4bca3a8fbb6f77c32b0ef784b77ebb172cdd6fd.
Reverted 0e78a7b40a19c0e76c215bb0e96e667476dbfea6
Merge remote-tracking branch 'upstream/master'