docs in Txbuilder
add docs to Address class
Merge pull request #314 from matiu/feature/docs02

Feature/docs02
remove eval

eval is unsafe, and the way it was being used in Script and Script interpreter
was not a good enough reason. This commit removes both uses of eval, then
replaces all uses of OP_XXX with Opcode.map.OP_XXX since there's no reason for
those constants to be global.
Merge pull request #321 from ryanxcharles/feature/remove-eval

Remove eval
remove unused chai dependency
Script is not used in this example
Merge pull request #323 from cimm/remove_unused_script_multisig_example

Script is not used in this example
add contributing.mdwq
Merge pull request #328 from maraoz/add/contributing

add contributing.md
Added EC Point multiplication to browser/Point.js
Implemented Armory style key derivation from chain code and public key (WIP)
Implemented Armory initializing from seed
Armory: cleaned up example
Armory: added descriptive log in examples/Armory.js
Fixed browser exception caused by lib/Curve.js
Armory: added to bitcore.js, build.js and browser example
Armory: fixed bug.. extra lines considered as real input
Armory: from master public key
Armory: added tests