Merge pull request #160 from lukechampine/client

Client signatures
touchups to the client-cli code
get siblings in UploadFile
begin implementation of the client struct
Merge branch 'master' into upload
add Init() to client
add type Keypair to siacrypto
client reorganization
add RSEncode to quorum
address bugs/improvements from PR comments
Merge pull request #162 from DavidVorick/upload

Major Changes to Client
slight tweak to well-tested, segfault-free code
sign entire script input
modify DefaultScript to remove redundant data

Since a signed message includes the original message, it didn't make
sense to append the input to the signed message. The default script
now moves the data pointer to the input inside the signed message.
Merge pull request #163 from lukechampine/scripting

Sign the entire script input
allow client to choose bootstrap hostname
allow server to retry connection
separate join quorum and establish quorum
display public key in hex
add support for choosing bootstrap port