Fix compilation error with some versions of node-0.9

[zuazo]

node-java compilation fails with node versions between v0.9.4 and v0.9.12. Tested with binary donwloadable versions from the official site. Gives the following error:

make: Entering directory `~/forks/node-java/build'
  ACTION Verify Deps build/depsVerified
  CXX(target) Release/obj.target/nodejavabridge_bindings/src/java.o
../src/java.cpp: In function ‘_jobject* Java_node_NodeDynamicProxyClass_callJs(JNIEnv*, _jobject*, jlong, _jobject*, _jobjectArray*)’:
../src/java.cpp:740: error: invalid conversion from ‘void (*)(uv_work_t*)’ to ‘void (*)(uv_work_t*, int)’
../src/java.cpp:740: error: initializing argument 4 of ‘int uv_queue_work(uv_loop_t*, uv_work_t*, void (*)(uv_work_t*), void (*)(uv_work_t*, int))’
make: *** [Release/obj.target/nodejavabridge_bindings/src/java.o] Error 1
make: Leaving directory `~/forks/node-java/build'

This PR solves the problem. Tested to work with multiple node versions between v.0.6.0 and v.0.11.1.

Perhaps related with the issue #43.