Lint and refact

[fredbi]

Major refactoring of expander

This PR is mostly refactoring and applies only minor change on behavior

Content

• Split up expander and separate swagger specific feature from schema generics (e.g. resolve ref)
• Remove duplicate code with parameter / response resolve/expand
• Modernize code style and abide by golangci linters
• Update bindata generation with kevinburke's fork
• Augment UT coverage

Fixups

Minor bug fixes:

• fixed Parameter.RemoveParam() func
• fixed non deterministic func Operation.SuccessReponse()

Integration tests

• [x] Integration tests with go-openapi/validate
• [x] Integration tests w/ go-swagger/go-swagger

[codecov[bot]]

Codecov Report

Merging #85 into master will increase coverage by 11.49%. The diff coverage is 75.73%.

@@             Coverage Diff             @@
##           master      #85       +/-   ##
===========================================
+ Coverage    46.3%   57.79%   +11.49%     
===========================================
  Files          19       22        +3     
  Lines        2149     2085       -64     
===========================================
+ Hits          995     1205      +210     
+ Misses        978      715      -263     
+ Partials      176      165       -11

Impacted Files	Coverage Δ
debug.go	100% <ø> (ø)	:arrow_up:
operation.go	92.85% <100%> (+43.63%)	:arrow_up:
cache.go	100% <100%> (ø)
info.go	59.7% <100%> (+1.73%)	:arrow_up:
header.go	54.65% <100%> (+33.72%)	:arrow_up:
response.go	62.74% <100%> (+36.33%)	:arrow_up:
swagger.go	56.92% <100%> (ø)	:arrow_up:
security_scheme.go	78% <100%> (+3%)	:arrow_up:
tag.go	42.1% <100%> (ø)	:arrow_up:
bindata.go	22.79% <17.64%> (-3.48%)	:arrow_down:
... and 16 more

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[fredbi]

Reported golangci failure: golangci/golangci#25

[fredbi]

Integration testing went okay for me

[fredbi]

What do we do with this one? I made it on purpose to be able to continue maintenance from a reduced debt. Anything left I should change?