Remove build configuration selection.

.travis.yml

@@ -7,7 +7,7 @@ d:
   # catching most DMD version related build failures early
   - dmd-2.071.0
   - ldc-1.0.0
-  - dmd-2.070.0
+  - dmd-2.070.2
 
 script: ./travis-ci.sh
 

travis-ci.sh

@@ -3,14 +3,14 @@
 set -e -x -o pipefail
 
 # test for successful release build
-dub build --combined -b release --compiler=$DC --config=${VIBED_DRIVER=libevent}
+dub build --combined -b release --compiler=$DC
 
 # test for successful 32-bit build
 if [ "$DC" == "dmd" ]; then
 	dub build --combined --arch=x86
 fi
 
-dub test --combined --compiler=$DC --config=${VIBED_DRIVER=libevent}
+dub test --combined --compiler=$DC
 
 if [ ${BUILD_EXAMPLE=1} -eq 1 ]; then
     for ex in $(\ls -1 examples/); do