Remove travis_wait

As it may not be required with latest stack which prints a line for each
module it compiles. Hopefully there are no modules which take more than
10 minutes to compile.

Author: akshaymankar

.travis.yml

@@ -223,7 +223,7 @@ script:
   set -ex
   case "$BUILD" in
     stack)
-      travis_wait 30 stack --no-terminal $ARGS test --bench --no-run-benchmarks --haddock --no-haddock-deps
+      stack --no-terminal $ARGS test --bench --no-run-benchmarks --haddock --no-haddock-deps
       ;;
     cabal)
       cabal install --enable-tests --enable-benchmarks --force-reinstalls --ghc-options=-O0 --reorder-goals --max-backjumps=-1 $CABALARGS $PACKAGES