Added in ability to add sections to a django email

[scornflake]

[codecov-io]

Codecov Report

Merging #63 into master will increase coverage by 1.31%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #63      +/-   ##
==========================================
+ Coverage   60.22%   61.53%   +1.31%     
==========================================
  Files           1        1              
  Lines          88       91       +3     
  Branches       22       24       +2     
==========================================
+ Hits           53       56       +3     
  Misses         29       29              
  Partials        6        6

Impacted Files	Coverage Δ
sgbackend/mail.py	61.53% <100%> (+1.31%)	:arrow_up:

---

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 476bfbe...5f817b0. Read the comment docs.

[andriisoldatenko]

@scornflake can you please add examples of usage to README.md

[andriisoldatenko]

@scornflake Please resolve conflict.