Fix compilation of AkkaHttpImplicits for Scala 2.11

[andreaTP]

The code generated for AkkaHttp is not compiling for Scala 2.11 The error is like following:

target/scala-2.11/src_managed/main/com/codacy/worker/api/specification/AkkaHttpImplicits.scala:92:46: missing parameter type for expanded function ((x$8) => {
[error]   <synthetic> <artifact> val x$9 = acc(value);
[error]   x$8.$colon$colon(x$9)
[error] })
[error]       accumulator.updateAndGet(acc(value) :: _)
[error]                                              ^
[error] one error found

Here you have the trivial fix.

[blast-hardcheese]

In our repos I believe we were using -Xexperimental to get around this, but this is a better fix. Thank you!

[blast-hardcheese]

In our repos I believe we were using -Xexperimental to get around this, but this is a better fix. Thank you!