Add rustfmt.toml and update travis to check formatting

.travis.yml

@@ -3,6 +3,12 @@ rust:
   - stable
   - beta
   - nightly
+before_script:
+  - rustup component add rustfmt-preview
+script:
+  - cargo fmt all -- --check
+  - cargo build
+  - cargo test
 matrix:
   allow_failures:
     - rust: nightly

rustfmt.toml

@@ -0,0 +1,17 @@
+indent_style = "Visual"
+format_strings = true
+format_macro_matchers = true
+imports_layout = "HorizontalVertical"
+merge_imports = true
+match_block_trailing_comma = true
+merge_derives = true
+newline_style = "Unix"
+normalize_comments = true
+reorder_impl_items = true
+space_after_colon = true
+space_before_colon = false
+struct_lit_single_line = false
+type_punctuation_density = "Wide"
+use_field_init_shorthand = true
+use_try_shorthand = true
+wrap_comments = true