clean up docs, tests, and refactor read pandas

[oscarbatori]

Some changes:

• remove Sphinx and docs
• remove redundant tests that now are in doltcli
• make Pandas reads use new doltcli ability to inject file parser to improve perf
• bump doltcli dep

[codecov-io]

Codecov Report

Merging #144 (4a13e85) into master (e7dfa97) will decrease coverage by 13.11%. The diff coverage is 68.88%.

@@             Coverage Diff             @@
##           master     #144       +/-   ##
===========================================
- Coverage   55.06%   41.95%   -13.12%     
===========================================
  Files          25       23        -2     
  Lines        1718      963      -755     
===========================================
- Hits          946      404      -542     
+ Misses        772      559      -213     

Impacted Files	Coverage Δ
doltpy/sql/__init__.py	100.00% <ø> (ø)
doltpy/sql/sync/__init__.py	0.00% <0.00%> (ø)
doltpy/sql/sync/dolt.py	0.00% <0.00%> (ø)
doltpy/sql/sql.py	77.05% <66.66%> (+0.09%)	:arrow_up:
doltpy/cli/__init__.py	100.00% <100.00%> (ø)
doltpy/cli/dolt.py	100.00% <100.00%> (+46.16%)	:arrow_up:
doltpy/cli/read.py	100.00% <100.00%> (ø)
doltpy/cli/write.py	100.00% <100.00%> (ø)
doltpy/etl/loaders.py	86.89% <100.00%> (ø)
doltpy/types/__init__.py	0.00% <0.00%> (-100.00%)	:arrow_down:
... and 4 more

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