Fix running tests on circle with linked packages and add status badge to readme

[TimMikeladze]

[alexyuly]

@TimMikeladze Is the idea that you want to link graphql-crud locally to graphql-crud-mongo before running its tests? Doesn't look like the existing graqhql-crud-mongo test imports anything from graphql-crud: https://github.com/TimMikeladze/graphql-crud/blob/master/packages/graphql-crud-mongo/test/MongoStore.test.ts

Anyway, I'd like to start contributing to this -- looking for a first issue. Looks like there may be a little housekeeping to do.

[TimMikeladze]

Check the dev branch Btw for the latest code