Do not convert keys that look like ints into ints

Razor::CLI::Navigate.move_to was converting a key that looked like an
integer to an integer, solely based on whether that conversion could be
done or not. That is wrong for several reasons, most importantly because
the data type of what we compare the key against in the documents received
from the server does and should not depend on whether something can be
represented as an integer or not.

In the code that used the converted key, it was used to either find an
entry in an array of hashes where the 'name' property of the entry matches
the key, or to retrieve an entry from the (Hash) document we are working
on. In both cases, what we compare the key to must be a string; if it is
not a string, that's a violation of the API contract, and the client's
behavior just glossed over that.