Fix friends edit for multi-word EDITORs

[JacobEvelyn]

Fixes #251

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Hi there! Thanks so much for submitting a pull request!

Let's just make sure together that all of these boxes are checked before we
merge this change:

• The code in these changes works correctly.
• Code has tests as appropriate.
• Code has been reviewed by @JacobEvelyn.
• All tests pass on Travis CI.
• Code coverage remains high.
• Rubocop reports no issues on Travis CI.
• The README.md file is updated as appropriate.

Don't worry—this list will get checked off in no time!

[codecov]

Codecov Report

Merging #252 into master will not change coverage by %.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #252   +/-   ##
=======================================
  Coverage   98.38%   98.38%           
=======================================
  Files          23       23           
  Lines         741      741           
=======================================
  Hits          729      729           
  Misses         12       12           

Impacted Files	Coverage Δ
lib/friends/commands/edit.rb	100.00% <100.00%> (ø)

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