Moves the TockEnv implementation of RNG to env/ (#599)

This change removes the tock dependencies from non-Tock envs.

libraries/rng256/Cargo.lock

@@ -50,47 +50,6 @@ version = "0.2.133"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c0f80d65747a3e43d1596c7c5492d95d5edddaabd45a7fcdb02b95f644164966"
 
-[[package]]
-name = "libtock_codegen"
-version = "0.1.0"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
-[[package]]
-name = "libtock_core"
-version = "0.1.0"
-dependencies = [
- "libtock_codegen",
-]
-
-[[package]]
-name = "libtock_drivers"
-version = "0.1.0"
-dependencies = [
- "libtock_core",
-]
-
-[[package]]
-name = "proc-macro2"
-version = "1.0.43"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0a2ca2c61bc9f3d74d2886294ab7b9853abd9c1ad903a3ac7815c58989bb7bab"
-dependencies = [
- "unicode-ident",
-]
-
-[[package]]
-name = "quote"
-version = "1.0.21"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bbe448f377a7d6961e30f5955f9b8d106c3f5e449d493ee1b125c1d43c2b5179"
-dependencies = [
- "proc-macro2",
-]
-
 [[package]]
 name = "rand"
 version = "0.6.5"
@@ -211,27 +170,9 @@ name = "rng256"
 version = "0.1.0"
 dependencies = [
  "arrayref",
- "libtock_drivers",
  "rand",
 ]
 
-[[package]]
-name = "syn"
-version = "1.0.100"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "52205623b1b0f064a4e71182c3b18ae902267282930c6d5462c91b859668426e"
-dependencies = [
- "proc-macro2",
- "quote",
- "unicode-ident",
-]
-
-[[package]]
-name = "unicode-ident"
-version = "1.0.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dcc811dc4066ac62f84f11307873c4850cb653bfa9b1719cee2bd2204a4bc5dd"
-
 [[package]]
 name = "winapi"
 version = "0.3.9"