[Objc] Enhancements and Issue fix

[geekerzp]

• Fix issue Incorrect objective-c #896

• Package objc client using cocoapods

• Support cli option

  CONFIG OPTIONS
  classPrefix
      prefix for generated classes (convention: Abbreviation of pod name e.g. `HN` for `HackerNews`), default: `SWG`
  
  podName
      cocoapods package name (convention: CameCase), default: `SwaggerClient`
  
  podVersion
      cocoapods package version, default: `1.0.0`

• Support file downloading for Objc API client

• Tested without issue:

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 37.738 s
[INFO] Finished at: 2015-06-26T09:41:10+08:00
[INFO] Final Memory: 11M/156M
[INFO] ------------------------------------------------------------------------

[wing328]

Test result looks good:

Test Suite 'StoreApiTest' passed at 2015-07-15 10:16:50 +0000.
     Executed 1 test, with 0 failures (0 unexpected) in 0.589 (0.589) seconds
Test Suite 'UserApiTest' started at 2015-07-15 10:16:50 +0000
Test Case '-[UserApiTest testLoginUser]' started.
2015-07-15 18:16:50.223 xctest[4068:24592] http://petstore.swagger.io/v2/user/login cache disabled
Test Case '-[UserApiTest testLoginUser]' passed (0.664 seconds).
Test Suite 'UserApiTest' passed at 2015-07-15 10:16:50 +0000.
     Executed 1 test, with 0 failures (0 unexpected) in 0.664 (0.664) seconds
Test Suite 'SwaggerClient_Tests.xctest' passed at 2015-07-15 10:16:50 +0000.
     Executed 14 tests, with 0 failures (0 unexpected) in 13.662 (13.670) seconds
Test Suite 'All tests' passed at 2015-07-15 10:16:50 +0000.
     Executed 14 tests, with 0 failures (0 unexpected) in 13.662 (13.672) seconds
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 28.046 s
[INFO] Finished at: 2015-07-15T18:16:51+08:00
[INFO] Final Memory: 11M/245M
[INFO] ------------------------------------------------------------------------