parsing numbers to string, setup will install requests 2.3.0, added link...

... to [jneureuther/est](https://github.com/jneureuther/est) in README

parsing numbers to string: I got errors, when ```lecture_id``` was a number because it should be a string
install requests 2.3.0: pip from the ubuntu package needs request 2.3.0. If you install the latest requests, pip won't work anymore.
added link to [jneureuther/est](https://github.com/jneureuther/est): When I searched [jneureuther/est](https://github.com/jneureuther/est), I only found [jneureuther/est_upload](https://github.com/jneureuther/est_upload)...