Add a custom context menu for nemo file manager

Nemo allows the user to add new entries to the context menu. The file /usr/share/nemo/actions/sample.nemo_action contains an example of a Nemo action. Directories to place custom action files:

/usr/share/nemo/actions/ for system-wide actions
~/.local/share/nemo/actions/ for user actions
Action files must have the .nemo_action file extension.