when subscribing to ConditionType

* Test for strings that aren't arrays, but start with a bracket

* Fix array-detection in string_to_val

* create private keys
* create self signed certficates
* create certifcate signing requests
* create ca for signing csr

The helpers are:
* generate_private_key
* generate_app_certificate_signing_request
* generate_self_signed_app_certificate
* sign_certificate_request

Test and example are available.

According to Part 4 - 7.10 this should be an a number that indicates how secure the EndPoint is. The number is Server implementation specific, how higher the number how saver.

* Fix for numvalues parameter in Node.read_raw_history()

* Fix for numvalues parameter in Node.read_raw_history() 2

* Update xmlparser.py

* Update xmlparser.py

* Update sync.py

add 'monitoring' and 'sampling_interval' params to subscribe_data_change in sync.py.

* Update sync.py

adds a method to the client to delete a subscription (using uaclient) and the associated sync method