Move KeywordMute into Glitch namespace.

There are two motivations for this:

1. It looks like we're going to add other features that require
   server-side storage (e.g. user notes).

2. Namespacing glitchsoc modifications is a good idea anyway: even if we
   do not end up doing (1), if upstream introduces a keyword-mute feature
   that also uses a "KeywordMute" model, we can avoid some merge
   conflicts this way and work on the more interesting task of
   choosing which implementation to use.

db/migrate/20171021191900_move_keyword_mutes_into_glitch_namespace.rb

@@ -0,0 +1,7 @@
+class MoveKeywordMutesIntoGlitchNamespace < ActiveRecord::Migration[5.1]
+  def change
+    safety_assured do
+      rename_table :keyword_mutes, :glitch_keyword_mutes
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20171010025614) do
+ActiveRecord::Schema.define(version: 20171021191900) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -155,6 +155,15 @@ ActiveRecord::Schema.define(version: 20171010025614) do
     t.index ["account_id", "target_account_id"], name: "index_follows_on_account_id_and_target_account_id", unique: true
   end
 
+  create_table "glitch_keyword_mutes", force: :cascade do |t|
+    t.bigint "account_id", null: false
+    t.string "keyword", null: false
+    t.boolean "whole_word", default: true, null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["account_id"], name: "index_glitch_keyword_mutes_on_account_id"
+  end
+
   create_table "imports", force: :cascade do |t|
     t.integer "type", null: false
     t.boolean "approved", default: false, null: false
@@ -167,15 +176,6 @@ ActiveRecord::Schema.define(version: 20171010025614) do
     t.bigint "account_id", null: false
   end
 
-  create_table "keyword_mutes", force: :cascade do |t|
-    t.bigint "account_id", null: false
-    t.string "keyword", null: false
-    t.boolean "whole_word", default: true, null: false
-    t.datetime "created_at", null: false
-    t.datetime "updated_at", null: false
-    t.index ["account_id"], name: "index_keyword_mutes_on_account_id"
-  end
-
   create_table "media_attachments", force: :cascade do |t|
     t.bigint "status_id"
     t.string "file_file_name"
@@ -481,8 +481,8 @@ ActiveRecord::Schema.define(version: 20171010025614) do
   add_foreign_key "follow_requests", "accounts", name: "fk_76d644b0e7", on_delete: :cascade
   add_foreign_key "follows", "accounts", column: "target_account_id", name: "fk_745ca29eac", on_delete: :cascade
   add_foreign_key "follows", "accounts", name: "fk_32ed1b5560", on_delete: :cascade
+  add_foreign_key "glitch_keyword_mutes", "accounts", on_delete: :cascade
   add_foreign_key "imports", "accounts", name: "fk_6db1b6e408", on_delete: :cascade
-  add_foreign_key "keyword_mutes", "accounts", on_delete: :cascade
   add_foreign_key "media_attachments", "accounts", name: "fk_96dd81e81b", on_delete: :nullify
   add_foreign_key "media_attachments", "statuses", on_delete: :nullify
   add_foreign_key "mentions", "accounts", name: "fk_970d43f9d1", on_delete: :cascade