MDL-13114 tool_uploadcourse: Initial commit
MDL-13114 tool_uploadcourse: Classes for course importation
MDL-13114 tool_uploadcourse: Unit tests for introduced classes
MDL-13114 tool_uploadcourse: Reset only allowed on update
MDL-13114 tool_uploadcourse: Improving the error reporting
MDL-13114 tool_uploadcourse: Processor can preview and log errors