The RippleAddress class was used to represent a number of fundamentally
different types: account public keys, account secret keys, node public
keys, node secret keys, seeds and generators.
The class is replaced by the following types:
* PublicKey for account and node public keys
* SecretKey for account and node private keys
* Generator for generating secp256k1 accounts
* Seed for account, node and generator seeds
* Remove cxx14 compatibility layer from ripple
* Update travis to clang 3.6 and drop gcc 4.8
* Remove unneeded beast CXX14 defines
* Do not run clang build with gdb with travis
* Update circle ci to clang 3.6 & gcc-5
* Don't run rippled in gdb, clang builds crash gdb
* Staticly link libstdc++, boost, ssl, & protobuf
* Support builds on ubuntu 15.10
