make mocha browser tests all run with no console errors

...except Wallet and WalletFactory.
initial work replacing symmetric shared secret with ECIES
add tests for changes to private key
add tests for WebRTC and fix some mocha browser test problems

from now on you need to run "grunt shell --target=dev" to build the test
version of copay which you can run the mocha browser tests on, which includes
packages like sinon and soop.
make WebRTC tests work
remove unused "copay" dependency
add some basic tests for WebRTC
another test for WebRTC
fix Wallet tests

...by removing references to now-nonexistent netKey
got WalletFactory tests to work

...by removing the reference to netKey
remove commented-out references to obsolete netKey
add private key in Wallet call to network start
add tests for Wallet
add tests for WalletFactory
bug: this -> self
Merge pull request #677 from ryanxcharles/feature/ECIES

ECIES