[L-05] Dangerous role setting

[madMax92221]

In SingeSidedReinsurancePool.sol we can observe the function setRole which sets a particular role for the given user. The problem here is that every person with a particular role can call this function and give the same role to everybody which can be problematic in some scenarios.

A better idea would be for one person, such as the admin, to have the ability to call that function and set all roles. This would be much more secure.

[wankhede04]

fixed at commit 917ceb3