Fix full-text search query quotation, improve tag search performance with an index,

add ability to open status by URL from search (fix #53)

db/migrate/20170322162804_add_search_index_to_tags.rb

@@ -0,0 +1,9 @@
+class AddSearchIndexToTags < ActiveRecord::Migration[5.0]
+  def up
+    execute 'CREATE INDEX hashtag_search_index ON tags USING gin(to_tsvector(\'simple\', tags.name));'
+  end
+
+  def down
+    remove_index :tags, name: :hashtag_search_index
+  end
+end