brownie 1.0.0b1

• major code re-organization, brownie now works as a package and is installable via pip
• remove os.path in favor of pathlib.Path - allow Windows support
• rebuild brownie console, use compile to check for completed statements
• remove Accounts.mnemonic
• transaction.history is now a custom data class
• save and load accounts using standard encrypted keystore files
• add brownie bake to initialize projects from template
• many bugfixes and minor changes