Elo-indexserver-client

* https://github.com/treskon/elo-indexserver-client/pull/18
* maputils: serialize_table, deserialize_table remove table_name parameter as it was a wrong assumption that elo uses best practices

* https://github.com/treskon/elo-indexserver-client/pull/17
* add serialize_map_fields_table and deserialize_map_fields_table: Helper Method to serializes, given the raw elo
map fields, a table like format. The table is represented as a list
of dictionaries, where each dictionary represents a row in the table.
All operations are done in memory and no ELO operations are performed.

PR:

* https://github.com/treskon/elo-indexserver-client/pull/16
* add a convenient method to automatically convert the obj_keys from a sord to a dict and cast them to their type
according to the config in the docmask.

PR:

* https://github.com/treskon/elo-indexserver-client/pull/12
* Read map fields

Details:

* Added read_map_fields method to EloService to read map fields from a sord
* Can load all map fields or only specific ones
* Can load strings or entire byte arrays
* Can load a specific map domain

PR:

* https://github.com/treskon/elo-indexserver-client/pull/14
* update method upload_file and update_file.
* https://github.com/treskon/elo-indexserver-client/pull/15
* Add a method to download a file by its sord_id

Details:
upload_file and update_file are now also setting the x_date_iso.
Automatically:

* the modified date of the file
Manually:
* can be set by the caller of the function.

i_date_iso = Time of the archiving - technical date on which the file was uploaded
x_date_iso = Primary document date (optional) - usecase dependent date, e.g. invoice date, contract date, etc.