Restoring bouncycastle Elliptic Curve Key support

Specific algorithms now available:
- KeyAgreement.ECDH
- KeyFactory.EC
- KeyPairGenerator.EC
- Signature.NONEWITHECDSA
- Signature.ECDSA
- Signature.SHA256WITHECDSA
- Signature.SHA384WITHECDSA
- Signature.SHA512WITHECDSA

Bug: 3058375
Change-Id: I611b23b2f72bb5d9898d4c695f1677c7914353c6
62 files changed