Add support for SEQUENCE OF ... DEFAULT

[rbalik]

This fixes issue #123 specifically for OCTET STRING types in the SEQUENCE
It's basically bare minimum for my specific application. Hopefully good enough to merge in, but happy to hear any feedback

[eerimoq]

Please add a test or two.

[codecov]

Codecov Report

Merging #139 (954cba0) into master (e1ecbac) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #139   +/-   ##
=======================================
  Coverage   35.68%   35.68%           
=======================================
  Files           7        7           
  Lines        8446     8446           
=======================================
  Hits         3014     3014           
  Misses       5432     5432           

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[coveralls]

Coverage decreased (-0.2%) to 95.139% when pulling 954cba0 on rbalik:sequenceofdefault into e1ecbac on eerimoq:master.