Rust 1.8 is not supported anymore for Serde

Serde 1.0 requires Rust 1.13

Author: rubdos

ci/test_full.sh

@@ -22,12 +22,11 @@ for feature in '' bigint rational complex; do
   cargo test --verbose --no-default-features --features="$feature"
 done
 
+if [ "$TRAVIS_RUST_VERSION" = 1.8.0 ]; then exit; fi
+
 # Build test for the serde feature
 cargo build --verbose --features "serde"
 
-
-if [ "$TRAVIS_RUST_VERSION" = 1.8.0 ]; then exit; fi
-
 # num-derive should build on 1.15.0+
 cargo build --verbose --manifest-path=derive/Cargo.toml