re-export WasmExecutionMethod for downstream usage (#239)

Signed-off-by: Gregory Hill <gregorydhill@outlook.com>

client/src/lib.rs

@@ -58,6 +58,7 @@ pub use sc_service::{
     config::{
         DatabaseConfig,
         KeystoreConfig,
+        WasmExecutionMethod,
     },
     Error as ServiceError,
 };
@@ -66,7 +67,6 @@ use sc_service::{
         NetworkConfiguration,
         TaskType,
         TelemetryEndpoints,
-        WasmExecutionMethod,
     },
     ChainSpec,
     Configuration,