Overhaul of the Reconstruction Pipeline to use a scanobj

[timwahoo]

Fixes #160

Changes proposed in this pull request:

• The entire recon.py file and recoFunction.py file has been rewritten to minimize passing large objects around
• recoSigpy.py file has been removed to not require SigPy as a brkraw requirement. The motivation for this move is to establish brkraw as an INTERMEDIATE for image reconstruction methods in MIRT, SigPy, and BART. A wrapper function and tutorial will added later for SigPy and BART.
• recon.py now contains a single class that takes a scanObj, certain acqp, meth, and reco variables necessary for FID sorting and simple image reconstruction. Users will have to option to either take the root mean square (rms) of the complex image.
• The Reconstruction object can return 3 numpy objects (readout sorted FID, processed kspace, and image reconstruction using a simple Fourier transformation. Compressed Sensing will return a zerofilled sorted kspace matrix
• Please look into recon_api_test.py for an example on how to create a nifti file from the reconobj.

@BrkRaw/Bruker