Scrapydd

* add a new spider setting "extra_settings" to control installing additional requirement of spider.
* support read config from environment variables.
* new docker build.
* override BOT_NAME by the project_name on the server side.

* new project egg download api.
* fix: error occured when project has no dependency.
* fix: server and client side memory leak every time need to get project dependency keep importing egg in current
process, now read requirements in egg(zip) file directly.
* move project operations into ProjectWorkspace, workspace execute in tmp folder on both server/agent side.
* add agent error log file.
* fix: requirement not correct when installing this package.

* add tag system.
* add database_url configuration

* job fail email nofitication.
* spider parameters.
* add config file location ./conf/scrapydd.conf

- fix: error occurred when modifying spider setting.

- agent: add configuration request_timeout
- fix: add_schedule.json occurs issue
- server & agent: kill process when job is timeout
- move webhook setting to spider settings