* feature/collector:
  modify worker num value

* feature/collector:
  timezone error
  import a deleted class
  no message
  mock mock mock

* fix httpclient issue
* @ascrutae As you pr too many commits, I will use `confirm squash and merge`.

fix start time of span is zero issue

Update readme file. And remove all images, move those resources to https://github.com/sky-walking/page-resources

* feature/collector:
  modify testcase bug When errors occur in timezone
  mock mock mock
  remove property layer and kind from node index

* feature/collector:
  dag graph finish
  dag graph reached a crossroads
  no message
  add dag node search service use jetty servlet
  no message

Fix typo, and remove unnecessary lock in NoConcurrencyAceessObject. Refact FileWriter and SnifferConfigInitializer.