Convert to our wrapper class for assertions

* Migrate assertions to Webmozart

* SQL: changed init session table so it will work on MSSQL Databases

* SQL: changed rowCount by count of fetchAll
rowCount does not always returns number of rows on SELECT queries, i.e. MSSQL returns -1

PSR-12 compliancy

* Rationalize SQL Store insertOrUpdate

* Handle duplicate insertion also for SQL Server
* Improve 'update or insert' handling for different SQL drivers

Makes no sense to use a protected constructor here.. In fact, it restricts is from unit-testing this class

Declaration of kvstore _expires field was defaulting to current
timestamp in MySQL.
Added mini upgrade script to kvstore init method to add default null
value.

I may be missing something but I haven't found a way to add the --ssl-ca
MySQL option to my database connection. It appears we just need to pass
in an $options param.

Formatting, namespaces, phpdoc.

Use LONGTEXT instead of the TEXT data type in MySQL to avoid size constraints in the latter. This resolves #399.

(being respectful with occurences that might change the behaviour, i.e. default database prefixes)