change all "not applicable" enum entries to not_applicable
add the not_applicable enum constants
Merge branch 'master' of https://github.com/mpi2/PhenotypeArchive

# By jwgwarren (6) and ckchen-ebi (2)
# Via jwgwarren
* 'master' of https://github.com/mpi2/PhenotypeArchive:
  number of images for a parameter added to images in impc section for gene page
  added to repos
  image comparator js changes
  fixed expression images not showing on gene page
  added SimpleOntoTerm class for hp term mapping of mp
  impc images working for gene page and images selector and comparator
  added google tracking to genomeBrowser page
  some comments added to tests after developer code review