Fix secret key encode and add secret key hash
Save keys to text file
Add load keys
Add save/load key test
Remove direct save and load from client
Reduce scope of keys
fix secret hash error test
Merge branch 'client'

Conflicts:
	src/siacrypto/signatures.go
resolve conflicts
Update to libsodium
Fix return statements
forgot a return
Merge pull request #152 from JoshVorick/client

Add save/load keys, add secret key hash, fix secret key encode