Refactor docs into mdbook (#547)

* Refactor documentation, ef_tests makefile

* Add makefile to root

* Tidy readme

* Fix readme badges

* Tidy logs

* Add terminalize gif

* Update readme image

* Update readme image

* Tidy logs

* Update readme image

* Update readme

* Update readme

* Fix book link

* Update makefiles

* Update book

* Fix link in book

* Add readme for book

* Remove old docs, move api spec YAML

* Fix eth2/ dir readme

* Add readme for lcli

* Add about this book section

* Minor formatting improvements

* Address mehdi's comments

book/src/ci.md

@@ -0,0 +1,33 @@
+# Contiguous Integration (CI) and Testing
+
+Lighthouse uses a self-hosted Gitlab CI server to run tests and deploy docs.
+
+For security reasons, **CI will only be run automatically for Lighthouse
+maintainers.** Contributors without maintainer privileges will need to have CI
+triggered for them prior to a PR being merged.
+
+You can see the full set of tests we run in the
+[gitlab-ci.yml](https://github.com/sigp/lighthouse/blob/master/.gitlab-ci.yml)
+file. The following two commands should complete successfully before CI can
+pass:
+
+```bash
+$ cargo test --all --all-features
+$ cargo fmt --all --check
+```
+
+_Note: Travis CI is also used, however it does not run the full test suite._
+
+### Ethereum 2.0 Spec Tests
+
+The
+[ethereum/eth2.0-spec-tests](https://github.com/ethereum/eth2.0-spec-tests/)
+repository contains a large set of tests that verify Lighthouse behaviour
+against the Ethereum Foundation specifications.
+
+These tests are quite large (100's of MB), so we don't download them by
+default. Developers should ensure they have downloaded these tests using the
+`Makefile` in
+[tests/ef_tests](https://github.com/sigp/lighthouse/tree/master/tests/ef_tests).
+
+**Failures in these tests should prevent CI from passing.**