Auto merge of #222 - SuperFluffy:serde_0.8, r=cuviper

Use serde 0.8

I updated `bigint`, `complex`, and `rational` to use `serde 0.8`, and also fixed deserialization and the `serde` feature as such in the `rational` crate (didn't add any tests, but it compiles now).

Similar to https://github.com/rust-num/num/pull/196 for `num/complex`, “`use serde;`” needed to be removed in `num/rational`.

.travis/test_nightly.sh

@@ -8,3 +8,7 @@ cargo test --verbose --manifest-path=macros/Cargo.toml
 
 # Build test for the serde feature
 cargo build --verbose --features "serde"
+
+# Downgrade serde and build test the 0.7.0 channel as well
+cargo update -p serde --precise 0.7.0
+cargo build --verbose --features "serde"

bigint/Cargo.toml

@@ -29,7 +29,7 @@ version = "0.3.19"
 
 [dependencies.serde]
 optional = true
-version = "0.7.0"
+version = ">= 0.7.0, < 0.9.0"
 
 [features]
 default = ["rand", "rustc-serialize"]

complex/Cargo.toml

@@ -22,7 +22,7 @@ version = "0.3.19"
 
 [dependencies.serde]
 optional = true
-version = "^0.7.0"
+version = ">= 0.7.0, < 0.9.0"
 
 [features]
 default = ["rustc-serialize"]

rational/Cargo.toml

@@ -30,7 +30,7 @@ version = "0.3.19"
 
 [dependencies.serde]
 optional = true
-version = "0.7.0"
+version = ">= 0.7.0, < 0.9.0"
 
 [features]
 default = ["bigint", "rustc-serialize"]