Merge branch 'polarssl-1.2' for release of PolarSSL 1.2.3
Inserted bump_version.sh in git repository
Memory leak when using RSA_PKCS_V21 operations fixed
Moved md_init_ctx() calls around to minimize exit points
Cleaner test-memory cleanups
Handle future version properly in ssl_write_certificate_request()
Fixed comment on maximum tested size for POLARSSL_MPI_MAX_LIMBS
Correctly handle CertificateRequest with empty DN list in <= TLS 1.1
Added ssl_handshake_step() to allow single stepping the handshake
process

Single stepping the handshake process allows for better support of
non-blocking network stacks and for getting information from specific
handshake messages if wanted.
Added PolarSSL 1.1.5 ChangeLog from 1.1 branch
Updated for PolarSSL 1.2.4