Xss fixes majortomsec

[danlipert]

Description

This PR fixes some POST/GET and potential XSS issues

Refers/Fixes

#5183

Testing

tested by OG bounty hunter

[codecov]

Codecov Report

Merging #5926 into master will decrease coverage by 0.07%.
The diff coverage is 11.11%.

@@            Coverage Diff             @@
##           master    #5926      +/-   ##
==========================================
- Coverage   29.39%   29.32%   -0.08%     
==========================================
  Files         270      270              
  Lines       23090    23106      +16     
  Branches     3353     3358       +5     
==========================================
- Hits         6788     6775      -13     
- Misses      16013    16033      +20     
- Partials      289      298       +9

Impacted Files	Coverage Δ
app/dashboard/views.py	11.61% <0%> (-0.02%)	⬇️
app/kudos/views.py	14.91% <11.11%> (-0.12%)	⬇️
app/dashboard/tip_views.py	15.9% <11.11%> (-0.22%)	⬇️
app/marketing/views.py	11.11% <11.11%> (-0.16%)	⬇️
app/dashboard/utils.py	40.81% <50%> (+0.03%)	⬆️
...eting/management/commands/assemble_leaderboards.py	50.42% <0%> (-3.4%)	⬇️
app/app/utils.py	22.07% <0%> (-0.67%)	⬇️
...rketing/management/commands/no_applicants_email.py	0% <0%> (ø)	⬆️

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