feat(server): change default dispatcher

- Deprecates the `no_proto` configuration on `Server`. It is always
  enabled.
- Deprecates all pieces related to tokio-proto.
- Makes the tokio-proto crate optional, and the `server-proto` feature
  can be used to completely remove the dependency. It is enabled by
  default.

.travis.yml

@@ -8,8 +8,9 @@ matrix:
           env: FEATURES="--features nightly"
         - rust: beta
         - rust: stable
+          env: HYPER_DOCS=1
         - rust: stable
-          env: HYPER_NO_PROTO=1
+          env: FEATURES="--no-default-features"
         - rust: stable
           env: FEATURES="--features compat"
         - rust: 1.17.0
@@ -37,7 +38,7 @@ addons:
 
 
 after_success:
-  - '[ $TRAVIS_RUST_VERSION = stable ] &&
+  - '[ "$HYPER_DOCS" = "1" ] &&
     LOCAL="~/.local" && export PATH=$LOCAL/bin:$PATH &&
     wget https://github.com/SimonKagstrom/kcov/archive/master.tar.gz &&
     tar xzf master.tar.gz && mkdir kcov-master/build && cd kcov-master/build &&
@@ -51,7 +52,7 @@ after_success:
       fi;
     done &&
     kcov --coveralls-id=$TRAVIS_JOB_ID --merge target/cov target/cov/*'
-  - '[ $TRAVIS_PULL_REQUEST = false ] && [ $TRAVIS_RUST_VERSION = stable ] &&
+  - '[ $TRAVIS_PULL_REQUEST = false ] && [ "$HYPER_DOCS" = "1" ] &&
     { [ "$TRAVIS_TAG" != "" ] || [ "$TRAVIS_BRANCH" == "master" ]; } &&
     ./.travis/docs.sh'