Maven Central Jar Compiled with Java 1.8?

When I switch my application to use the latest `1.0.1` version of this jar and pull it from Maven Central, I get the following exception:

```
Exception in thread "main" java.lang.UnsupportedClassVersionError: com/amazon/sqs/javamessaging/ExtendedClientConfiguration : Unsupported major.minor version 52.0, compiling:(/tmp/form-init8767020834767061108.clj:1:73)
at clojure.lang.Compiler.load(Compiler.java:7391)
at clojure.lang.Compiler.loadFile(Compiler.java:7317)
at clojure.main$load_script.invokeStatic(main.clj:275)
at clojure.main$init_opt.invokeStatic(main.clj:277)
at clojure.main$init_opt.invoke(main.clj:277)
at clojure.main$initialize.invokeStatic(main.clj:308)
at clojure.main$null_opt.invokeStatic(main.clj:342)
at clojure.main$null_opt.invoke(main.clj:339)
at clojure.main$main.invokeStatic(main.clj:421)
at clojure.main$main.doInvoke(main.clj:384)
at clojure.lang.RestFn.invoke(RestFn.java:421)
at clojure.lang.Var.invoke(Var.java:383)
at clojure.lang.AFn.applyToHelper(AFn.java:156)
at clojure.lang.Var.applyTo(Var.java:700)
at clojure.main.main(main.java:37)
Caused by: java.lang.UnsupportedClassVersionError: com/amazon/sqs/javamessaging/ExtendedClientConfiguration : Unsupported major.minor version 52.0
```

I see in the `pom.xml` the compiler plugin is set to use Java 1.7 - is it possible though that the jar pushed to Maven Central was built with the wrong JDK?

For what it's worth, if I clone this repo and build it using my 1.7 JDK, I stop experiencing the error.

Thanks!