Add psycopg2 wrapper

[kolanos]

Closes #344

[codecov]

Codecov Report

Merging #350 into master will increase coverage by 0.02%.
The diff coverage is 86.41%.

@@            Coverage Diff             @@
##           master     #350      +/-   ##
==========================================
+ Coverage   85.92%   85.94%   +0.02%     
==========================================
  Files          38       39       +1     
  Lines        1513     1594      +81     
==========================================
+ Hits         1300     1370      +70     
- Misses        213      224      +11

Impacted Files	Coverage Δ
iopipe/contrib/trace/auto_db.py	91.83% <82.45%> (-5.95%)	⬇️
iopipe/contrib/trace/dbapi.py	95.83% <95.83%> (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 ad4538e...b4be93f. Read the comment docs.

[mrickard]

👍