making Jedis compatible with CDI

When using CDI and trying to produce a `Jedis` and `JedisPool` we got an exception because CDI needs default constructor to make the object proxy.

Here is some project showing the problem: https://github.com/nykolaslima/cdiProblem

This change creates default constructor for `Jedis` and `JedisPool` classes. This constructor should only be used by CDI, thats why I added a `@Deprecated`.