Remove exclude_paths

Exclude paths have been deprecated for some time. To avoid confusion, I
think it's time we remove them completely.

Author: wfleming

SPEC.md

@@ -18,12 +18,7 @@ Engines can define their own appropriate configuration keys and values, based on
 their needs. A developer invoking a Code Climate engine stores their configuration
 for all engines in a single `.codeclimate.yml` file. The Code Climate CLI (and other tools compatible with Code Climate Engines) parse and interpret the YAML file to produce a single, simple JSON config object for each engine.
 
-Certain keys of the config object will be passed to all engines, and must be respected in order to conform with the specification. There are two keys, both related to which files to analyze:
-
-* `include_paths`
-* `exclude_paths` (deprecated)
-
-These are covered in detail below.
+The `include_paths` key will always be present in `config.json`, and must be used by engines to limit which files they will analyze. Details of this key are below.
 
 ### Which files to analyze
 
@@ -41,8 +36,6 @@ These are covered in detail below.
 
 `include_paths` may include paths to files that are irrelevant to the analysis (i.e., `.gitignore` if the engine only analyzes JavaScript). Engines are responsible for filtering out irrelevant files.
 
-`exclude_paths` is deprecated in favor of `include_paths`. `exclude_paths` is an array of file paths (relative to the `/code` directory) that should be ignored for the purposes of analysis. No Issues should be emitted for excluded files.
-
 ## Output
 
 Engines stream static analysis Issues to STDOUT in JSON format. When possible, results should be emitted as soon as they are computed (streaming, not buffered). Each issue is terminated by the [null character][null] (`\0` in most programming languages), but can additionally be separated by newlines.