Small improve in README.md and bower.json.

- npm should never be capitalized (https://www.npmjs.org/doc/misc/npm-faq.html#is-it-npm-or-npm-or-npm-).
- remove unnecessary slashes in urls (README.md).
- https use instead git (git is used for ssh keys).
- add build.gradle to bower ignore.
- remove unnecessary `./` on `main` section in bower.json.