Run a development node by default during `nile run`

[ericglau]

trafficstars

As a developer, I want a local (short-lived) development node to be run by default when I run a script using nile run, so that I don't need to start a node manually when testing my script.

Notes:

• Consider using separate (or temporary) accounts/declarations/deployment files for this scenario (differentiating from localhost), since the deployments in this scenario may not be relevant between runs.

[martriay]

the PR addressing this should be mindful of other possible node instances running at the same time