tools: remove JSON schema validation tool

I'm now using the json_schema gem which already includes such a tool.

src/tools/json-schema-validate.rb

@@ -1,17 +0,0 @@
-#!/usr/bin/env ruby
-
-require 'json'
-require 'jschema'
-
-fail "Required parameters: <schema> <file to validate>" if ARGV.count != 2
-
-content     = JSON.parse File.read(ARGV[1])
-schema_data = JSON.parse File.read(ARGV[0])
-schema      = JSchema.build(schema_data)
-errors      = schema.validate content
-
-exit 0 if errors.empty?
-
-puts errors.join("\n")
-
-exit 1