Remove the IE 11 fullscreen externs declarations

They are defined in recent versions of Closure Compiler.
Use build.js for ol.js
Use build.js for ol-simple.js
Use build.js for ol-whitespace.js
Use build.js for ol-all.js
Use serve.js instead of the Plovr server
Add jquery-1.7 externs
Fix a type issue in jquery-1.7 externs

See https://github.com/google/closure-compiler/issues/176
Use build.js for compiling the examples
Use build.js for compiling the examples all at once
Use closure-util's Closure lib for the check-requires target
Make compiler happy by replacing 0e6 by 0
compilation_level is now just ADVANCED and SIMPLE
Remove some externs declarations

All these declarations are defined in recent versions of Closure Compiler.
Get Closure Library from closure-util for host-examples
Refresh the compiler error list

Based on https://github.com/openlayers/closure-util/blob/master/compiler-options.txt
Use serve.js as the test server
Update .travis.yml
Target integration-test renamed to ci
Remove ununsed serve-integration-test target