Add options for disabling column family encryption and choosing hash algorithm for wrapped encryption keys.

<!-- markdown --> This change adds options for disabling column family encryption and choosing hash algorithm for wrapped encryption keys. Changes are done such that defaults will keep the same behavior prior to this issue.      Prior to this change HBase always used the MD5 hash algorithm to store a hash for encryption keys. This hash is needed to verify the secret key of the subject. (e.g. making sure that the same secrey key is used during encrypted HFile read and write). The MD5 algorithm is considered weak, and can not be used in some (e.g. FIPS compliant) clusters. Having a configurable hash enables us to use newer and more secure hash algorithms like SHA-384 or SHA-512 (which are FIPS compliant). The hash is set via the configuration option `hbase.crypto.key.hash.algorithm`. It should be set to a JDK `MessageDigest` algorithm like "MD5", "SHA-256" or "SHA-384". The default is "MD5" for backward compatibility. Alternatively, clusters which rely on an encryption at rest mechanism outside of HBase (e.g. those offered by HDFS) and wish to ensure HBase's encryption at rest system is inactive can set `hbase.crypto.enabled` to `false`.