Added webservice

syntax:
{
"username":"cristianhalman",
"password":"password",
"date":"2013-09-30 18:47:58",
"date_due":"2013-09-30 18:47:58",
"status":"0",
"billLines":
[{
"description":"DESCRIPTION",
"amount_total":"20000",
"amount_paid_by_insurance":"0",
"amount_paid_by_user":"0"
},
{
"description":"DESCRIPTION2",
"amount_total":"30000",
"amount_paid_by_insurance":"0",
"amount_paid_by_user":"0"
}]
}