Auto merge of #56 - nox:core-graphics, r=KiChjang

Update core-graphics to 0.7

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Author: bors-servo

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "core-text"
-version = "3.0.0"
+version = "4.0.0"
 authors = ["The Servo Project Developers"]
 description = "Bindings to the Core Text framework."
 license = "MIT/Apache-2.0"
@@ -11,4 +11,4 @@ libc = "0.2"
 
 [target.x86_64-apple-darwin.dependencies]
 core-foundation = "0.3"
-core-graphics = "0.6"
+core-graphics = "0.7"