Support presto Decimal, Date and Timestamp types

[devinstevenson]

Hi @jingw.

I added support on Presto for decimal, date, and timestamp presto types. I also modified the tests to include a date type. The Travis CI test failed on python 3.6 seems to be a Travis CI issue. The tests passed on all other versions of python.

[codecov-io]

Codecov Report

Merging #171 into master will decrease coverage by 0.24%.
The diff coverage is 97.56%.

@@ Coverage Diff @@## master #171 +/- ##
==========================================
- Coverage 95.71% 95.47% -0.25% 
==========================================
Files 14 14 Lines 1422 1457 +35 Branches 147 149 +2 ==========================================
+ Hits 1361 1391 +30 - Misses 40 44 +4 - Partials 21 22 +1

Impacted Files	Coverage Δ
pyhive/tests/test_hive.py	97.7% <ø> (ø)	⬆️
pyhive/tests/test_presto.py	96.36% <ø> (-3.64%)	⬇️
pyhive/tests/test_sqlalchemy_hive.py	100% <100%> (ø)	⬆️
pyhive/presto.py	94% <100%> (+0.38%)	⬆️
pyhive/tests/test_sqlalchemy_presto.py	100% <100%> (ø)	⬆️
pyhive/sqlalchemy_presto.py	91.97% <95.45%> (+0.59%)	⬆️
pyhive/hive.py	90.09% <0%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b68e1a8...85ebb50. Read the comment docs.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}