Add snippet for ledger

Signed-off-by: Rene Vergara <rene.a.vergara@gmail.com>
Add a snippet to enter a transaction into a ledger file to be
used with the ledger accounting tool.

Recommend to use the vim-ledger plugin for filetype detection.

UltiSnips/ledger.snippets

@@ -0,0 +1,6 @@
+snippet t "Transaction" b
+${1:`!v strftime("%Y")`}-${2:`!v strftime("%m")`}-${3:`!v strftime("%d")`} ${4:*} ${5:Payee}
+	${6:Expenses} 			\$${7:0.00}
+	${8:Assets:Checking}
+
+endsnippet