misc: create license and readme

README.md

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+# Arbiter
+> Policy-first multi-client wallet daemon, allowing permissioned transactions across blockchains
+
+## Security warning
+Arbiter can't meaningfully protect against host compromise. Potential attack flow:
+- Attacker steals TLS keys from database
+- Pretends to be server; just accepts user agent challenge solutions
+- Pretend to be in sealed state and performing DH with client
+- Steals user password and derives seal key
+
+While this attack is highly targetive, it's still possible. 
+
+> This software is experimental. Do not use with funds you cannot afford to lose.