Updated Requests

- added Date and Account field to Saved Requests
- requests are now saved as dict()
  old requests will be deleted!!
- Account field is hidden when only 1 account is available
- address line now follows the current_account
- saved requests is sortable, default sorted by date
- saved requests only shows request for current_account
add NotEnoughFunds exception
remove deprecated files from app.fil
set data_files only when install is invoked
update README with pip
Fix currency type for bitcoinvenezuela history

update exchange rate history for bitcoinvenezuela exchange
fix column number for monospace font (amount)
Merge branch 'contacts' of github.com:Tafelpoot/electrum into Tafelpoot-contacts
various fixes for reveive_requests
Merge branch 'Tafelpoot-contacts'
add invalid password check
pass absolute path for new wallet
Merge pull request #947 from Tafelpoot/walletpath2

pass absolute path for new wallet
Merge pull request #944 from tkhaew/priv_keys_pwd

Issue #941 fix export_privkeys_dialog, add invalid password check
add InvalidPassword exception
do not add command to console history if it starts with a space
not bip39 anymore