Show all signature matches when trying to bucket a crash.

[jschwartzentruber]

Searching for matching buckets for an unbucketed crash only shows "good" matches, where "good" is fairly arbitrary. Instead show all matches (ordered by quality of the match), and let the user decide.

[codecov[bot]]

Codecov Report

Merging #593 into master will decrease coverage by <.01%. The diff coverage is 5.4%.

@@            Coverage Diff             @@
##           master     #593      +/-   ##
==========================================
- Coverage   66.02%   66.01%   -0.01%     
==========================================
  Files          80       80              
  Lines        7976     7975       -1     
==========================================
- Hits         5266     5265       -1     
  Misses       2710     2710

Impacted Files	Coverage Δ
server/crashmanager/views.py	65.11% <5.4%> (-0.05%)	:arrow_down:

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[jschwartzentruber]

@choller pointed out that this was a necessary optimization because for many signatures, searching all buckets would be unacceptably slow.

needs further thought to see if both goals can be achieved. (performant and showing more matches)