The ESDK only supports compressed ECDSA keys

[seebees]

Roughly we need to hit include:

• the DefaultCMM MUST ONLY read and write compressed ECDSA public keys
• the compression that is used MUST be that defined in SEC1-v2 section 2.3.3

[mattsb42-aws]

related to #118

[mattsb42-aws]

breadcrumb: http://www.secg.org/sec1-v2.pdf
section 2.3.3 describes point compression

[mattsb42-aws]

moving decompression check to #150