feat(less): Automate importing src/app and src/common less files into main.less

Any less files found in 'src/app' and 'src/common' will be automatically imported into the base of the 'src/less/main.less' file at build time.

To achieve this the build process must make a temporary copy of the main.less file, append a string of imports to the base of this file, use it as the target of the recess compilation process, and then then delete the temporary file. 

This may not be the most ideal solution, but it allows users to drag and drop folders into their projects 'app' and 'common' directories without worrying about adding their less imports to the main.less file.

The advantage to including the less files as imports is that the 'src/app' less files can still exploit any less variables that have been defined in app.less. However, this approach may encourage bad practices with the 'src/common' less files.