Try to Reduce Watch CPU Usage

This commit adds a `lazy mode` to `watch` and changes the default options hash that `watch` passes to `Listen`

`Watch` runs in `lazy mode` by default. In this mode, `watch` only fires the following rules when there are added or removed files, ignoring file modification. The `lazy mode` behavior can be overridden by giving options with `{ lazy : false}`.

When there's no options given, `watch` will use the default options, which will check for changes every 10 seconds and ignore the downloading files.

Try to resolve maid#149

lib/maid/watch.rb

@@ -6,7 +6,14 @@ class Maid::Watch
 
  def initialize(maid, path, options = {}, &rules)
  @maid = maid
- @options = options
+ if options.nil? 
+ @lazy = true
+ @options = { wait_for_delay: 10, 
+ ignore: [/\.crdownload$/, /\.download$/, /\.aria2$/, /\.td$/, /\.td.cfg$/, /\.part$/] }
+ else
+ @lazy = options.delete(:lazy) { |key| true }
+ @options = options
+ end
  @logger = maid.logger # TODO: Maybe it's better to create seperate loggers?
  @path = File.expand_path(path)
  initialize_rules(&rules)
@@ -15,7 +22,9 @@ def initialize(maid, path, options = {}, &rules)
  def run
  unless rules.empty?
  @listener = Listen.to(path, @options) do |modified, added, removed|
- follow_rules(modified, added, removed)
+ if !@lazy || added.any? || removed.any?
+ follow_rules(modified, added, removed)
+ end
  end
  @listener.start
  end