Implement /schedule command

[dgongut]

Note: This will be a major update (goes to version 3.0.0) since it requires a volume to save the schedules.

It is envisaged to include the functionality of scheduling.

It should work as follows:

• /schedule <run/stop/restart>
• /schedule (without anything else)

First case When the user introduce a complete command.

The program should store it in a file. For example:

• /schedule 0 2 * * * restart firefox

It should save in a file the following sentence
0 2 * * *|restart|firefox

The bot must check the cron every minute for any of the records that need to be executed.

Second case The user introduces the command without parameters.

When the user introduce /schedule without parameters it should display all the records in buttons (1 column). Clicking in one of them should be delete it from the file.

[dgongut]

Done in version 3.0.0