Add "Default Ripple" account flag and associated logic:

AccountSet set/clear, asfDefaultRipple = 8

AccountRoot flag, lsfDefaultRipple = 0x00800000

In trustCreate, set no ripple flag if appropriate.

If an account does not have the default ripple flag set,
new ripple lines created as a result of its offers being
taken or people creating trust lines to it have no ripple
set by that account's side automatically

Trust lines can be deleted if the no ripple flag matches
its default setting based on the account's default ripple
setting.

Fix default no-rippling in integration tests.

test/ledger-state.coffee

@@ -491,8 +491,9 @@ exports.LedgerState = class LedgerState
 
   add_transaction_fees: ->
     extra_fees = {}
+    account_sets = ([k] for k,ac of @accounts)
     fee = Amount.from_json(@remote.fee_cushion * 10)
-    for list in [@trusts, @iou_payments, @offers]
+    for list in [@trusts, @iou_payments, @offers, account_sets]
       for [src, args...] in list
         extra = extra_fees[src]
         extra = if extra? then extra.add(fee) else fee
@@ -526,6 +527,13 @@ exports.LedgerState = class LedgerState
                LOG("Account `#{src}` creating account `#{dest}` by "+
                      "making payment of #{amt.to_text_full()}") ),
             cb)
+      (cb) ->
+        reqs.transactor(
+          Transaction::account_set,
+          accounts_apply_arguments,
+          ((account, tx) ->
+            tx.tx_json.SetFlag = 8
+          ), cb)
       (cb) ->
         reqs.transactor(
             Transaction::ripple_line_set,