moved build command to packcage.json
README: typos
Merge pull request #22 from zw/master

Fix PoLtree link.
Update README.md
improved introductory paragraph
Merge branch 'master' of github.com:olalonde/proof-of-liabilities

Conflicts:
	README.md
README: added timestamp and currency properties to root serialization specification
README: fixed unix timestamp reference
README: modified currency specification
removed deprecated blproof.js