Improved Binary Handling in Document Tree by adding several tree representations:
* Allow access to all array bytes using the same tree representation for the binary array like
  json array are tree parts.
* Decode strings using UTF-8 and UTF-16.
* Test if byte arrays can be converted to numeric values (checking the
  byte array length). Tested types are: short, integer, long, float, double.
  These conversions use the default byte order of the JVM instance Umongo runs with.
Allow to choose the JSON serializer mode Legacy or Strict when
exporting documents to files.
Merge branch 'better-binary-handling' of https://github.com/inno-steffg/umongo.git into better-binary-handling