Extract MIES labnotebook reading into separate pip package

[t-b]

https://github.com/AllenInstitute/neuroanalysis/blob/master/neuroanalysis/miesnwb.py#L29

[campagnola]

Sounds good to me.

However: what do you think about taking all of miesnwb.py? The reason is that it implements a set of (not finalized) data structures that are meant to present an API for accessing patch clamp data that is independent of the acquisition system. The goal is that anyone who writes analysis tools from that API will not have to worry about where their data came from. We are already using this to support 3 different backends in synphys, and @dyf and I have started making plans to merge this API with the one implemented in https://github.com/AllenInstitute/allensdk.ipfx/blob/master/allensdk/ipfx/ephys_data_set.py

Either way, the labnotebook reading can be implemented as a standalone function so that it's possible to do just that parsing for users not interested in the data abstraction bits.

[t-b]

@campagnola The idea of making the pip package small is that the maintance burden is minimal. Hopefully the labnotebook reading code remains stable.

I'll revisit the scope once I'm actually start working on it.