Merge branch 'key_store_and_accounts_integration' of https://github.com/Gustav-Simonsson/go-ethereum into Gustav-Simonsson-key_store_and_accounts_integration

Now using git instead of mercurial

* Use crypto.Sign instead of directly calling secp256k1 lib
* Rename UserAccount to Account and Addr to Address (for consistency)
* Change AccountManager.Sign to take ptr to Account instead of
  address byte array
* Simplify copying of Accounts in Accounts()
* PubkeyToAddress and GetEntropyCSPRNG now exported

Merge branch 'key_store_and_accounts_integration' of https://github.com/Gustav-Simonsson/go-ethereum into Gustav-Simonsson-key_store_and_accounts_integration

* Add initial UserAccount and AccountManager structs
* Add NewAccount, Sign and Accounts functions
* Refactor key stores to use key address as main identifier
  while keeping the UUID.
* Use key address as file/dir names instead of UUID

Merge branch 'import_presale_keys' of https://github.com/Gustav-Simonsson/go-ethereum into Gustav-Simonsson-import_presale_keys

Conflicts:
	crypto/crypto.go

* Browser now has tabs
* Fixed a callback issue

* ImportPreSaleKey takes a KeyStore, a presale key JSON (e.g. file content)
  and a password string. It stores the key in the given key store.
* Refactored common AES decryption and moved some functions to crypto.go