Fixed duplicate label translations for secondary itemsets and use itextID for selects with choices that have media specified

[DavisRayM]

Closes #464, #463

Why is this the best possible solution? Were any other approaches considered?

What are the regression risks?

None.

Does this change require updates to documentation? If so, please file an issue here and include the link below.

No

Before submitting this PR, please make sure you have:

• [x] included test cases for core behavior and edge cases in tests_v1
• [x] run nosetests and verified all tests pass
• [x] run black pyxform to format code
• [x] verified that any code or assets from external sources are properly credited in comments

[codecov-commenter]

Codecov Report

Merging #467 into master will increase coverage by 0.14%. The diff coverage is 97.61%.

@@            Coverage Diff             @@
##           master     #467      +/-   ##
==========================================
+ Coverage   83.39%   83.53%   +0.14%     
==========================================
  Files          25       25              
  Lines        3601     3633      +32     
  Branches      836      842       +6     
==========================================
+ Hits         3003     3035      +32     
  Misses        454      454              
  Partials      144      144              

Impacted Files	Coverage Δ
pyxform/xform2json.py	79.59% <88.88%> (+0.17%)	:arrow_up:
pyxform/question.py	92.95% <100.00%> (+0.10%)	:arrow_up:
pyxform/survey.py	91.88% <100.00%> (+0.36%)	:arrow_up:
pyxform/survey_element.py	94.71% <100.00%> (+0.27%)	: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 50921a8...f79ade9. Read the comment docs.

[DavisRayM]

Closing this in favor of #468. I didn't probably document my steps here or my reasoning for some of the changes. Most changes made here are actually not needed in order to fix the tagged issues. #468 is cleaner and I believe a bit more documented.