ENH: Make wrangler more verbose

[mgxd]

Closes #283

Adds verbose parameter, which enables logging through the find_estimators() process.

I think this could also benefit from a way to visualize the layout, to further help debug why files are not being found.

[codecov-commenter]

Codecov Report

Base: 83.12% // Head: 87.26% // Increases project coverage by +4.13% 🎉

Coverage data is based on head (54233eb) compared to base (6061ed8).
Patch coverage: 97.87% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #284      +/-   ##
==========================================
+ Coverage   83.12%   87.26%   +4.13%     
==========================================
  Files          26       25       -1     
  Lines        1956     1979      +23     
  Branches      295      297       +2     
==========================================
+ Hits         1626     1727     +101     
+ Misses        295      219      -76     
+ Partials       35       33       -2     

Flag	Coverage Δ
travis	83.27% <97.87%> (+0.14%)	⬆️
unittests	87.16% <97.87%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
sdcflows/utils/wrangler.py	97.11% <97.14%> (-0.42%)	⬇️
sdcflows/cli/find_estimators.py	88.88% <100.00%> (+0.25%)	⬆️
sdcflows/utils/misc.py	100.00% <100.00%> (ø)
sdcflows/__init__.py
sdcflows/workflows/outputs.py	93.54% <0.00%> (+1.61%)	⬆️
sdcflows/interfaces/reportlets.py	89.83% <0.00%> (+1.69%)	⬆️
sdcflows/interfaces/bspline.py	88.00% <0.00%> (+4.00%)	⬆️
sdcflows/interfaces/fmap.py	87.35% <0.00%> (+14.94%)	⬆️
sdcflows/workflows/fit/syn.py	69.82% <0.00%> (+21.30%)	⬆️
sdcflows/utils/phasemanip.py	94.02% <0.00%> (+28.35%)	⬆️

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[oesteban]

I would allow fMRIPrep and such to pass in their own logger objects.