Freeze enforcing: (RIPD-399)

* Set enforce date: September 15, 2014
 * Enforce in stand alone mode
 * Enforce at source
 * Enforce intermediary nodes
 * Enforce global freeze in get paths out
 * Enforce global freeze in create offer
 * Don't consider frozen links a path out
 * Handle in getBookPage
 * Enforce in new offer transactors

src/ripple/module/data/protocol/TER.cpp

@@ -51,6 +51,7 @@ bool transResultInfo (TER terCode, std::string& strToken, std::string& strHuman)
         {   tecNO_AUTH,             "tecNO_AUTH",               "Not authorized to hold asset."                         },
         {   tecNO_LINE,             "tecNO_LINE",               "No such line."                                         },
         {   tecINSUFF_FEE,          "tecINSUFF_FEE",            "Insufficient balance to pay fee."                      },
+        {   tecFROZEN,              "tecFROZEN",                "Asset is frozen."                                      },
 
         {   tefALREADY,             "tefALREADY",               "The exact transaction was already in this ledger."     },
         {   tefBAD_ADD_AUTH,        "tefBAD_ADD_AUTH",          "Not authorized to add account."                        },

src/ripple/module/data/protocol/TER.h

@@ -184,6 +184,7 @@ enum TER    // aka TransactionEngineResult
     tecNO_AUTH                  = 134,
     tecNO_LINE                  = 135,
     tecINSUFF_FEE               = 136,
+    tecFROZEN                   = 137,
 };
 
 inline bool isTelLocal(TER x)