fix lein run failing to run with overtone and lein2

Nice app!

I was getting the below error on lein run and lein 2 preview 10 until I applied this per overtone/overtone#108

```sh
$ lein run                                                                                                                                                                                                                                 [6:08:13]
Compiling overtoneinterface.server
Exception in thread "main" java.lang.RuntimeException: java.lang.Exception: Error in checker for ugen send-reply. Error: after initialisation, not all inputs to this ugen were numbers or other ugens (inputs which are explicitly allowed to be other data types (i.e strings)
 will have been converted to numbers at this point): [0 -1.0 12 47 115 101 114 118 101 114 45 105 110 102 111 #overtone.sc.machinery.ugen.sc_ugen.SCUGen{:id 1, :name "SampleRate", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1} #overtone.sc.machinery.ugen.sc_
ugen.SCUGen{:id 2, :name "SampleDur", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1} #overtone.sc.machinery.ugen.sc_ugen.SCUGen{:id 3, :name "RadiansPerSample", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1} #overtone.sc.machinery.ugen.sc_ugen.
SCUGen{:id 4, :name "ControlRate", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1} #overtone.sc.machinery.ugen.sc_ugen.SCUGen{:id 5, :name "ControlDur", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1} #overtone.sc.machinery.ugen.sc_ugen.SCUGen{:i
d 6, :name "SubsampleOffset", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1} #overtone.sc.machinery.ugen.sc_ugen.SCUGen{:id 7, :name "NumOutputBuses", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1} #overtone.sc.machinery.ugen.sc_ugen.SCUGen{:id
 8, :name "NumInputBuses", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1} #overtone.sc.machinery.ugen.sc_ugen.SCUGen{:id 9, :name "NumAudioBuses", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1} #overtone.sc.machinery.ugen.sc_ugen.SCUGen{:id 10,
 :name "NumControlBuses", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1} #overtone.sc.machinery.ugen.sc_ugen.SCUGen{:id 11, :name "NumBuffers", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1} #overtone.sc.machinery.ugen.sc_ugen.SCUGen{:id 12, :n
ame "NumRunningSynths", :rate 0, :rate-name :ir, :special 0, :args (), :n-outputs 1}], compiling:(info.clj:15)
        at clojure.lang.Compiler$InvokeExpr.eval(Compiler.java:3342)
        at clojure.lang.Compiler.compile1(Compiler.java:6985)
        at clojure.lang.Compiler.compile(Compiler.java:7046)
        at clojure.lang.RT.compile(RT.java:385)
        at clojure.lang.RT.load(RT.java:425)
        at clojure.lang.RT.load(RT.java:398)
        at clojure.core$load$fn__4610.invoke(core.clj:5386)
        at clojure.core$load.doInvoke(core.clj:5385)
        at clojure.lang.RestFn.invoke(RestFn.java:408)
        at clojure.core$load_one.invoke(core.clj:5200)
        at clojure.core$load_lib.doInvoke(core.clj:5237)
        at clojure.lang.RestFn.applyTo(RestFn.java:142)
        at clojure.core$apply.invoke(core.clj:602)
        at clojure.core$load_libs.doInvoke(core.clj:5275)
        at clojure.lang.RestFn.applyTo(RestFn.java:137)
        at clojure.core$apply.invoke(core.clj:602)
        at clojure.core$require.doInvoke(core.clj:5352)
        at clojure.lang.RestFn.invoke(RestFn.java:1096)
```