ECSignature: avoid multiple push/unshift operations
HDNode: enforces sane seed lengths
HDNode: fix error spelling
Transaction: add assertion that scriptPubKey exists
Merge pull request #242 from dcousens/hdstrict

HDNode: enforces sane seed lengths and Transaction input
HDNode: missing space in assertion message
upgrade browserify

per security advisory: https://nodesecurity.io/advisories/syntax-error-potential-script-injection
drop unnecessary binary paths
package: consistent path finding
package: no longer need to specify custom crypto-browserify
Transaction: remove signing operations
txbuilder stuff