adds chapter "Installation" and "Searching" for Bower
bower chapter fixes
Merge branch 'chapters-bower' of https://github.com/PascalPrecht/book-of-modern-frontend-tooling into chapter-bower
Minor revisions to Bower chapter

Update, fix typos and rephrase sentences on bower getting-started

Rephrase sentence on discovering/searching section
Merge pull request #70 from joaostein/bower-revision

Minor revision on Bower chapter