Fix container stop and destroy procedure

[grembo]

These commands erroneously appended taskCfg.Args to both commands, resulting in various undesirable outcomes, depending on the value if taskCfg.Args. One obvious problem is, that the appended "-F" to pot-destroy never came into effect. Args starting with "-" could also make the commands do different things or fail completely.

While investigating, I found that there are more things wrong with this (partially due to how pot handles things).

As a result, this change removes using the stop command and instead relies on calling destroy -F. Destroying the container is done exactly one (enforced using an atomic counter), so double-destroy, which happened in the past and messed up things, should not happen anymore.

While there, bump plugin version.

[grembo]

There's more to it, I will fix and expand this.

[grembo]

@pizzamig @ebarriosjr Now this should be much cleaner. I haven't tested this in our staging environment yet, but I think there is a non-zero chance this will actually fix bsdpot/pot#272

[grembo]

@ebarriosjr Thanks for the review