Move the wasmtime crate directories form lib/* to wasmtime-*.

This follows a similar change to Cranelift made here:

https://github.com/CraneStation/cranelift/pull/660

wasmtime-environ/Cargo.toml

@@ -0,0 +1,31 @@
+[package]
+name = "wasmtime-environ"
+version = "0.1.0"
+authors = ["The Wasmtime Project Developers"]
+description = "Standalone environment support for WebAsssembly code in Cranelift"
+repository = "https://github.com/CraneStation/wasmtime"
+documentation = "https://docs.rs/wasmtime-environ/"
+categories = ["wasm"]
+keywords = ["webassembly", "wasm"]
+license = "Apache-2.0 WITH LLVM-exception"
+readme = "README.md"
+edition = "2018"
+
+[dependencies]
+cranelift-codegen = "0.29.0"
+cranelift-entity = "0.29.0"
+cranelift-wasm = "0.29.0"
+cast = { version = "0.2.2", default-features = false }
+failure = { version = "0.1.3", default-features = false }
+failure_derive = { version = "0.1.3", default-features = false }
+indexmap = "1.0.2"
+rayon = "1.0"
+
+[features]
+default = ["std"]
+std = ["cranelift-codegen/std", "cranelift-wasm/std"]
+core = ["cranelift-codegen/core", "cranelift-wasm/core"]
+
+[badges]
+maintenance = { status = "experimental" }
+travis-ci = { repository = "CraneStation/wasmtime" }