Add face definition for `ledger-font-payee-pending-face'.

Ledger fontifies payees on pending transactions using the aptly named
`ledger-font-payee-pending-face' face, despite that face not actually
being defined. This patch fixes that.
Merge pull request #325 from sykora/master

Add face definition for `ledger-font-payee-pending-face'.

Ooops.  Missed that.  thank you!