bucket type riak-admin commands

this PR relies on https://github.com/basho/riak_core/pull/402, https://github.com/basho/riak_kv/pull/673, and https://github.com/basho/riak_kv/pull/677

* [ ] apply patch to riak_ee

Examples:
```
$ riak-admin bucket-type status atype
atype is not an existing bucket type

$ riak-admin bucket-type create atype '{"props": {"n_val": 5, "allow_mult": true}}'
atype created

$ riak-admin bucket-type status atype
atype has been created and may be activated

<<"n_val">>: 5
<<"allow_mult">>: true
precommit: []
postcommit: []
n_val: 3
last_write_wins: false
chash_keyfun: {riak_core_util,chash_std_keyfun}
allow_mult: false
active: false
claimant: 'dev1@127.0.0.1'

$ riak-admin bucket-type activate atype
atype has been activated

$ riak-admin bucket-type status atype
atype is active
....

$ riak-admin bucket-type list
test (active)
reallylongbuckettypenamethatmaycauseproblemsfordisplay (not active)
atype (active)

$ riak-admin bucket-type update atype '{"props": {"n_val": 9}}'
atype updated

$ riak-admin bucket-type reset atype
atype reset
```