Create API for checking Crawler's status

[sb-github]

API should give following information:

• number of records in DB;
• record's status: crawler, parser or graph phase.

[AlexanderTorchynskyi]

Created an endpoint for getting information about crawler current progress, endpoint to check: 192.168.128.245:8081/extractor/rest/v1/progress?crawler_id=5a71c5ce46e0fb0007adc6c0
The response will have this view:

1/4 - This means that crawler started its work;
2/4 - This means that vacancies have been parsed into parsed_vacancy table 
3/4 - This means that graph maker started grabbing vacancies from parsed_vacancy table 
4/4 - Graph is built