Merge pull request #11 from redink/master

add lists type for `Keys`

You can now specify a path into an EJSON object using either a tuple or a list. The following are now both accepted and equivalent:

```
ej:get({"a", "b"}, Obj),

ej:get(["a", "b"], Obj),

```
Remove unreachable code and quiet dialyzer warning
Update travis config for Erlang versions

- Add R16B02

- Remove some older releases from testing. I don't think there's
  anything that doesn't work there, but testing latest patch of a
  release is enough.
Consolidate type specs for keys to ej_key_path() type

Now that lists and tuples are supported, it makes sense to have a type
for key paths to simplify specs for get/set/delete.

Also fixed missing part of spec for key_type() to include the array
matching `{select, V}` stuff.
Enhance docs for get and set_p

Also cleaned up trailing whitespace.
Fix travis config, R16B should work, not yet R16B02
Merge pull request #1 from seth/master

update type define from seth