chore(power-assert): use "files" property, not .npmignore
feat(power-assert): update empower and power-assert-formatter to 0.8.0
chore(power-assert): rebuild web bundle
chore(power-assert): update dependencies
chore(power-assert): update examples
chore(power-assert): update dependencies
chore(power-assert): update browserify
chore(power-assert): replace obsoleted gulp-clean with del
chore(power-assert): replace obsoleted gulp-connect with gulp-webserver
chore(power-assert): does not require es5-shim even if using phantomjs
feat(power-assert): use single index.js

Say farewell to UMD and hello to browserify.
docs(CHANGELOG): create CHANGELOG.md
docs(README): reorganize README
Merge pull request #10 from twada/rel-0_8_0

Prepare for Release 0.8.0