Check if instance is still running

[samdfonseca]

Adds a check to make sure that reused bees are still running. If 3 instances are found in the ~/.bees file but 1 has been terminated, bees init -s 3 ... will bring up 1 new instance, and remove the terminated instance from the state file.

beeswithmachineguns git:(allow-create-extra-bees) ✗ cat ~/.bees
newsapps
bees
us-east-1d
i-9bfb3130
i-bbde1410
i-3cc60c97

beeswithmachineguns git:(allow-create-extra-bees) ✗ ./bees up -s 3 -g public -k bees
Read 3 bees from the roster.
Connecting to the hive.
Attempting to call up 1 bees.
Waiting for bees to load their machine guns...
.
.
.
.
.
.
Bee i-d50fc57e is ready for the attack.
The swarm has assembled 3 bees.

beeswithmachineguns git:(allow-create-extra-bees) ✗ cat ~/.bees
newsapps
bees
us-east-1d
i-d50fc57e
i-9bfb3130
i-3cc60c97

[samdfonseca]

@cosmin any interest in merging this?