Deprecate use of OpenAPI 2.0 (#55)

Fully deprecates the use of OpenAPI 2.0 (we've noted in the README that
it's been deprecated roughly ~forever) by:

* No longer copying it or its fixtures out of our source directory.
* Moving the existing files to a new `DEPRECATED_openapi` directory so
  that they're no longer part of the core set.
* Updating the README to reflect the changes.

README.md

@@ -10,10 +10,15 @@ Files can be found in the `openapi/` directory:
     * Contains special annotations, deprecated endpoints, and pre-release
       features specifically intended to support generating Stripe API
       libraries. Users should use the `spec3.{json,yaml}` variant instead.
-* `spec2.{json,yaml}`: OpenAPI 2.0 spec. We're continuing to generate this for
-  now, but it will be deprecated in favor of `spec3`.
 * `fixtures3.{json,yaml}`: Test fixtures for resources in `spec3`. See below
   for more information.
+
+We used to support OpenAPI 2.0, but have since deprecated its use, and it's no
+longer receiving updates. It will still be available in `DEPRECATED_openapi`
+for the next few months:
+
+* `spec2.{json,yaml}`: OpenAPI 2.0 spec. No longer receiving updates.
+  Deprecated in favor of `spec3`.
 * `fixtures2.{json,yaml}`: Test fixtures for resources in `spec2`.
 
 ## Vendor Extensions

bin/update

@@ -101,7 +101,7 @@ class Updater
     out.puts "--> Pulling from origin"
     out.puts utils.git_pull_origin_master
 
-    ["fixtures2", "fixtures3", "spec2", "spec3", "spec3.sdk", "spec3.java.sdk"].each do |file|
+    ["fixtures3", "spec3", "spec3.sdk", "spec3.java.sdk"].each do |file|
       source = File.join(SOURCE_DIR, "openapi", file + ".yaml")
       target = File.join(TARGET_DIR, "openapi", file + ".yaml")
 
@@ -172,7 +172,7 @@ else
 
       utils.expect(:git_pull_origin_master, "")
 
-      ["fixtures2", "fixtures3", "spec2", "spec3", "spec3.sdk", "spec3.java.sdk"].each do |file|
+      ["fixtures3", "spec3", "spec3.sdk", "spec3.java.sdk"].each do |file|
         source = File.join(Updater::SOURCE_DIR, "openapi", file + ".yaml")
         target = File.join(Updater::TARGET_DIR, "openapi", file + ".yaml")
 
@@ -188,19 +188,19 @@ else
         [Updater::TARGET_DIR])
 
       utils.expect(:dir_glob,
-        ["fixtures2.json", "fixtures2.yaml", "fixtures3.json", "fixtures3.yaml"],
+        ["fixtures3.json", "fixtures3.yaml"],
         ["#{Updater::TARGET_DIR}/openapi/fixtures*"])
       utils.expect(:git_add, "",
-        [["fixtures2.json", "fixtures2.yaml", "fixtures3.json", "fixtures3.yaml"]])
+        [["fixtures3.json", "fixtures3.yaml"]])
       utils.expect(:git_any_files_staged?, true)
       utils.expect(:git_commit, "",
         ["Update fixture data"])
 
       utils.expect(:dir_glob,
-        ["spec2.json", "spec2.yaml", "spec3.json", "spec3.yaml", "spec3.sdk.yaml", "spec3.sdk.json", "spec3.java.sdk.yaml", "spec3.java.sdk.json"],
+        ["spec3.json", "spec3.yaml", "spec3.sdk.yaml", "spec3.sdk.json", "spec3.java.sdk.yaml", "spec3.java.sdk.json"],
         ["#{Updater::TARGET_DIR}/openapi/spec*"])
       utils.expect(:git_add, "",
-        [["spec2.json", "spec2.yaml", "spec3.json", "spec3.yaml", "spec3.sdk.yaml", "spec3.sdk.json", "spec3.java.sdk.yaml", "spec3.java.sdk.json"]])
+        [["spec3.json", "spec3.yaml", "spec3.sdk.yaml", "spec3.sdk.json", "spec3.java.sdk.yaml", "spec3.java.sdk.json"]])
       utils.expect(:git_any_files_staged?, true)
       utils.expect(:git_commit, "",
         ["Update OpenAPI specification"])
@@ -254,7 +254,7 @@ else
 
       utils.expect(:git_pull_origin_master, "")
 
-      ["fixtures2", "fixtures3", "spec2", "spec3", "spec3.sdk", "spec3.java.sdk"].each do |file|
+      ["fixtures3", "spec3", "spec3.sdk", "spec3.java.sdk"].each do |file|
         source = File.join(Updater::SOURCE_DIR, "openapi", file + ".yaml")
         target = File.join(Updater::TARGET_DIR, "openapi", file + ".yaml")