fix(log): fix panic error when building app log message

[bacongobbler]

closes #136 by catching when the pod name fails the pod regex.

[deis-bot]

@jchauncey and @krancour are potential reviewers of this pull request based on my analysis of git blame information. Thanks @bacongobbler!

[codecov-io]

Codecov Report

Merging #139 into master will increase coverage by 0.63%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #139      +/-   ##
=========================================
+ Coverage   49.87%   50.5%   +0.63%     
=========================================
  Files          13      13              
  Lines         391     396       +5     
=========================================
+ Hits          195     200       +5     
  Misses        172     172              
  Partials       24      24

Impacted Files	Coverage Δ
log/message_handler.go	100% <100%> (ø)	⬆️

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