ci: bump MSRV to Rust 1.30.0

This simplifies testing quickcheck_macros on Rust stable and keeps the
trains running.

.travis.yml

@@ -1,14 +1,12 @@
 language: rust
 rust:
-  - 1.24.1
+  - 1.30.0
   - stable
   - beta
   - nightly
 script:
   - cargo build --verbose
   - cargo test --verbose
   - cargo doc
-  - if [ "$TRAVIS_RUST_VERSION" != "1.24.1" ]; then
-      cargo build --verbose --manifest-path quickcheck_macros/Cargo.toml;
-      cargo test --verbose --manifest-path quickcheck_macros/Cargo.toml;
-    fi
+  - cargo build --verbose --manifest-path quickcheck_macros/Cargo.toml
+  - cargo test --verbose --manifest-path quickcheck_macros/Cargo.toml

Cargo.toml

@@ -12,6 +12,9 @@ categories = ["development-tools::testing"]
 license = "Unlicense/MIT"
 exclude = ["/.travis.yml", "/Makefile", "/ctags.rust", "/session.vim"]
 
+[workspace]
+members = ["quickcheck_macros"]
+
 [features]
 default = ["regex", "use_logging"]
 unstable = []