Extend theme helper to show themes on answer pages

[pixeldesu]

Fixes #231

[codecov]

Codecov Report

Merging #248 (51bb2ae) into master (a78cb2f) will increase coverage by 0.10%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #248      +/-   ##
==========================================
+ Coverage   62.32%   62.43%   +0.10%     
==========================================
  Files          92       92              
  Lines        2121     2127       +6     
==========================================
+ Hits         1322     1328       +6     
  Misses        799      799              

Impacted Files	Coverage Δ
app/helpers/theme_helper.rb	100.00% <100.00%> (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 a78cb2f...51bb2ae. Read the comment docs.