update npm to 1.4.10 before install to fix ^ dependency

- travis ci uses npm 1.2.x for node 0.8.x
- npm install with npm 1.2.x fails due to lack of
backward compatibility of ^ dependency
- updating npm to 1.4.x should fix the failing npm
install for node 0.8.x
- Latest npm version at the moment is 1.4.11, though
updating from npm 1.2.x to 1.4.11 fails due to ^
dependency. https://github.com/npm/npm/issues/5318
- Until the bug is fixed, install npm 1.4.10