Setup clippy and rustfmt. Add a design to the README.

Author: gavadinov

README.md

@@ -12,3 +12,6 @@ A distributed in memory key-value database. This is a toy database implemented a
  - [ ] **Replication**
  - [ ] **Sharding**
  - [ ] **Local Dev** (Docker?)
+
+## [Initial] High Level Design
+![Design](r_db-high-level-design.png)

rustfmt.toml

@@ -0,0 +1 @@
+edition = "2018"

src/main.rs

@@ -1,3 +1,5 @@
+#![warn(clippy::all)]
+
 fn main() {
     println!("Hello, world!");
 }