Fix --no-default-features build, bump to v0.7.13

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "dipstick"
-version = "0.7.12"
+version = "0.7.13"
 authors = ["Francis Lalonde <fralalonde@gmail.com>"]
 
 description = """A fast, all-purpose metrics library decoupling instrumentation from reporting backends.

Makefile

@@ -19,7 +19,7 @@ CARGO_BUILD_FLAGS ?=
 
 # 'test' is a friendly alias for 'unit_test'
 test:
-	$(CARGO_CMD) test --features="skeptic"
+	$(CARGO_CMD) test --no-default-features --features="skeptic"
 
 examples:
 	$(CARGO_CMD) build --examples

README.md

@@ -77,7 +77,7 @@ To use Dipstick in your project, add the following line to your `Cargo.toml`
 in the `[dependencies]` section:
 
 ```toml
-dipstick = "0.7.11"
+dipstick = "0.7.13"
 ```
 
 ## External features

src/output/graphite.rs

@@ -102,7 +102,7 @@ impl OutputScope for GraphiteScope {
 impl Flush for GraphiteScope {
     fn flush(&self) -> error::Result<()> {
         self.notify_flush_listeners();
-        let buf = self.buffer.write();
+        let buf = write_lock!(self.buffer);
         self.flush_inner(buf)
     }
 }