TorBrowser.app.meek-http-helper symlinks incompatible with Gatekeeper signing

Experimentation shows that the symlink approach that we currently use to create a meek-specific "copy" of Tor Browser on Mac OS is not compatible with Apple's Gatekeeper code signing. Apple's codesign command complains about an invalid Info.plist because it is checking that the application binary (firefox) is where the Info.plist says it is and symlinks are apparently not traversed.

One possible solution is to eliminate the TorBrowser.app.meek-http-helper linked app bundle and add support to firefox for a command line option that causes the application to run as a background app. See https://trac.torproject.org/projects/tor/ticket/11429#comment:8 for more info.

Perhaps if we make the call to TransformProcessType() very early during firefox startup the problem that occurred before (dock icon appearing briefly during startup of the meek browser) will not occur. Another possibility is to change the Info.plist for Tor Browser so that the dock icon is hidden by default and then un-hide it when not running as the meek helper browser.