WIP - Standalone update installer with no dependency on Qt
Set platform defines correctly in Platform.h
Move intToStr() utility method to StringUtils header
Implement ProcessUtils::waitForProcess() using code from Qt updater

Also fix a typo in UpdateInstaller::run()
Add the core logic for installing and uninstalling files in UpdateInstaller
Start implementing the Unix versions of functions in FileOps
Implement Unix version of dirname()
Add minizip library and use it to implement extraction of files from zip archives.
Add more detailed information to any file I/O errors and return true from FileOps::removeFile() if the file does not exist.
Display a more helpful error message if waitpid() fails in ProcessUtils::waitForProcess()
Fix FileOps::touch()

creat() returns -1 on error or an fd otherwise which should be closed.
Add more detailed logging in the body of UpdateInstaller::run()
Implement temp package directory removal on Unix.  Untested.
Add code to launch applications with elevated priviledges on Mac from the old updater.
Use boost threads to run the update installation on a background thread.
Add entry type information at the start of each log file entry.
Add methods to UpdateScript to retrieve the path which the script was parsed from
Add a log entry if an unrecognized updater mode string is encountered.
Add FileOps method to get the canonical path for a file and the Unix implementation.
Get launching of the main update installer process working in the case where elevation is not required.

 * Add ProcessUtils::currentProcessPath() to get the path to the current application
   and add a Linux implementation.
 * Implement ProcessUtils::runAsync() on Unix using fork/execve.
 * Setup updater to run the main installation phase with the correct arguments.
 * Add '.zip' to the package name to get the path of the package file.