Engine downloader API for #31 (#42)

* Add is_engine_available_to_download API call

* Fix issue with worker never throwing error if engine is not found

* Add API call to get most recent engine version

* Fix some minor import issues

* Fix web urls

* Fix default server log level

* Add progress bar for project download worker_factory downloads missing engine versions

* Better error handling when invalid version is given

* Add timeouts to engine downloaders

src/utilities/misc_helper.py

@@ -110,3 +110,11 @@ def system_safe_path(path):
     if platform.system().lower() == "windows":
         return os.path.normpath(path)
     return path.replace("\\", "/")
+
+
+def current_system_os():
+    return platform.system().lower().replace('darwin', 'macos')
+
+
+def current_system_cpu():
+    return platform.machine().lower().replace('amd64', 'x64')