add test confirming that edn-java rejects ::keywords

edn-format/edn#44 suggests a clarification of the spec to make explicit
that ::keywords are not supported by edn (having no concept of
current namespace).
add test showing that edn-java currently accepts leading zeros in ints

edn-format/edn#33 raises this problem that the current informal spec
seems to allow leading zeros on integers without specifying their
semantics.

clojure.core/read and clojure.edn/read both interpret a redundant
leading zero as indicating that the numeric literal is to be interpreted
as octal, such that:

    077 -> 63
    078 -> throws an Exception

edn-java accepts leading zeros, but gives them no particular
significance:

    077 -> 77
    078 -> 78

Presumably, the correct thing for end to do would be to forbid leading
zeros on integer literals.
add test showing that edn-java currently accepts leading zeros on floats

edn-format/edn#33 raises this problem that the current informal spec
seems to allow leading zeros on integers without specifying their
semantics.

It turns out that this is relevant for floating point literals as well.
README.md (the current informal edn standard) is pretty clear about
forbidding supurfluous leading zeros in the integer and exponent
portion of floating point numbers.

Nonetheless, these leading zeros are accepted by edn-java,
clojure.core/read and clojure.edn/read.

In this case, all three implementations simply ignore the leading
zeros. (In the case of integer literals, clojure.core/read and
clojure.edn/read both take a leading zero as a signal to interpret the
remainder of the integer as written in octal.
Merge branch 'feature/tests' into develop

* feature/tests:
  add test showing that edn-java currently accepts leading zeros on floats
  add test showing that edn-java currently accepts leading zeros in ints
  add test confirming that edn-java rejects ::keywords