Feature 2152

added tests save and load cert in memory and file
added travis file

added serialize/desialize keys to cert_save_mem/cert_mem_load

added a few dap_hash_fast_xxx() functions

Feature 2152

update from master

[+] Check pkey part function

add dap_chain_sign_get_size()

fix dap_chain_sign_create()

[+] Pkey and signature operations. Data signing
[+] Signature verification

[+] PKey and Sign serialization structures operations

[+] File storage format (skeleton)
[-] Useless funcs with pkey serialization