Add support of optional parameters to Ruby codegen

[xhh]

Assuming name and status are optional parameters (required is false), instead of having to pass those two parameters like this:

PetApi.updatePetWithForm(1, "pet name", "pet status")

this PR allows passing any parameters that is needed, e.g. only update the status:

PetApi.updatePetWithForm(1, :status => "pet status")

Complete changes:

• Pass optional parameters via the opts Hash
• Handle query parameters in a way similar to header/form parameters to
  support parameter name normalization, e.g. the "additional_metadata"
  key is used for "additionalMetadata"
• Rename variables to be consistent: query_params, header_params and
  form_params
• Remove unnecessary blank lines
• Rename local variable body to _body_param to avoid potential naming comflict

[xhh]

FYI. the ruby integration test pass successfully:

$ mvn integration-test -rf :RubyPetstoreClientTests
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Ruby Swagger Petstore Client 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:2.8:copy-dependencies (default) @ RubyPetstoreClientTests ---
[INFO]
[INFO] --- exec-maven-plugin:1.2.1:exec (bundle-install) @ RubyPetstoreClientTests ---
Resolving dependencies...
Using ZenTest 4.11.0
Using addressable 2.3.8
Using autotest 4.4.6
Using ffi 1.9.8
Using sys-uname 0.9.2
Using autotest-fsevent 0.2.10
Using autotest-growl 0.2.16
Using autotest-rails-pure 4.1.2
Using safe_yaml 1.0.4
Using crack 0.4.2
Using diff-lcs 1.2.5
Using ethon 0.7.3
Using json 1.8.2
Using rspec-support 3.2.2
Using rspec-core 3.2.2
Using rspec-expectations 3.2.0
Using rspec-mocks 3.2.1
Using rspec 3.2.0
Using typhoeus 0.7.1
Using swagger-client 4.06.08 from source at .
Using vcr 2.9.3
Using webmock 1.21.0
Using bundler 1.7.7
Your bundle is complete!
Use `bundle show [gemname]` to see where a bundled gem is installed.
[INFO]
[INFO] --- exec-maven-plugin:1.2.1:exec (bundle-test) @ RubyPetstoreClientTests ---
.............................................

Finished in 25.88 seconds (files took 0.35215 seconds to load)
45 examples, 0 failures

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 30.335 s
[INFO] Finished at: 2015-04-16T18:39:37+08:00
[INFO] Final Memory: 11M/156M
[INFO] ------------------------------------------------------------------------