Make compatible with EphysCellFeatureExtractor (this might need a wrapper so dc can be passed as a parameter among other things.)

[jnsbck]

This should only be tackled after closing #4 . Should be part of v0.0.2 release.

Integrate the additional features and diagnostic functionality better with the AllenSDK package.

[jnsbck]

Also depends on implementing ramp and short square features.