add jbrowse integration back as a option in settings.py

[hsiaoyi0504]

No description provided.

[coveralls]

Coverage increased (+2.4%) to 40.22% when pulling a9098d1 on jbrowse_as_an_option into f178813 on master.

[codecov]

Codecov Report

Merging #119 into master will decrease coverage by 4.71%.
The diff coverage is 78.57%.

@@            Coverage Diff             @@
##           master     #119      +/-   ##
==========================================
- Coverage   52.42%   47.71%   -4.72%     
==========================================
  Files          72       69       -3     
  Lines        3151     3483     +332     
==========================================
+ Hits         1652     1662      +10     
- Misses       1499     1821     +322

Impacted Files	Coverage Δ
blast/models.py	78.12% <100%> (+25%)	⬆️
blast/admin.py	77.08% <40%> (-2.04%)	⬇️
blast/tasks.py	66.66% <66.66%> (+52.45%)	⬆️
i5k/settings.py	93.4% <80%> (-0.85%)	⬇️
blast/tests.py	30.36% <92.85%> (ø)
filebrowser/templatetags/fb_tags.py	17.97% <0%> (-39.33%)	⬇️
filebrowser/templatetags/fb_versions.py	21.92% <0%> (-38.6%)	⬇️
filebrowser/views.py	18.42% <0%> (-37.18%)	⬇️
filebrowser/functions.py	29.44% <0%> (-27.23%)	⬇️
filebrowser/templatetags/fb_csrf.py	42.1% <0%> (-26.32%)	⬇️
... and 19 more

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[ifishlin]

It looks good

[childers]

I think these changes look fine.