update README and build after simdcomp subtree refactor

.gitignore

@@ -5,3 +5,4 @@ target/release
 Cargo.lock
 benchmark
 .DS_Store
+cpp/simdcomp/bitpackingbenchmark

.travis.yml

@@ -1,11 +1,6 @@
 language: rust
 rust:
   - nightly
-git:
-  submodules: false
-before_install:
-  - sed -i 's/git@github.com:/https:\/\/github.com\//' .gitmodules
-  - git submodule update --init --recursive
 env:
   global:
     - CC=gcc-4.8

README.md

@@ -40,8 +40,6 @@ the submodules. The project can then be built using `cargo`.
 
     git clone git@github.com:tantivy-search/tantivy.git
     cd tantivy
-    git submodule init
-    git submodule update
     cargo build