Support pip & apt package items as inputs

[yadudoc]

Support pip, apt resources in addition to the current S3 and HTTP resources.
Pros:

1. This helps track provenance information relevant to resources that went into a job. A secondary feature would be a toggle for the user to specify that the job should be run with exactly the same version.
2. Fetching resources from the internet is ideally done outside the execution script. This allows us to run the script code without outgoing connections.

Cons:

1. Compatibility with older jobs ?
2. If the user uses some exotic package management system, supporting that is added work the worker has to do. Say, some julia/R package?