Bug 1361341 - Add rust clippy to mozlint r=ahal

Cargo.toml

docs/code-quality/lint/linters/clippy.rst

taskcluster/ci/source-test/python.yml

tools/lint/clippy.yml

tools/lint/clippy/__init__.py

tools/lint/test/files/clippy/test1/Cargo.toml

tools/lint/test/files/clippy/test1/bad.rs

tools/lint/test/files/clippy/test1/bad2.rs

tools/lint/test/files/clippy/test1/good.rs

tools/lint/test/files/clippy/test2/Cargo.toml

tools/lint/test/files/clippy/test2/src/bad_1.rs

tools/lint/test/files/clippy/test2/src/bad_2.rs

tools/lint/test/python.ini

tools/lint/test/test_clippy.py