Added SSL for Indy

Needs a standardized way of which type of certificates and ssl
connections are allowed.
Made it possible to call rest methods with nil
Fixed bug. Headers in Indy was not cleared
WinHTTP now raises an error like Indy
Added standard exception for both WinHTTP and Indy.
Make headers in Indy work more like WinHTTP
Empty HTTP response now returns empty object (nil)
Bug fix.

For some reason a TList<T> with less or more than 4 objects adds some
extra empty objects. A TList<T> with 5 objects adds 3 nil objects...
Merge branch 'master' of https://github.com/thomaserlang/delphi-rest-client-api into thomaserlang-master
Fixed tests broken after standardizing exception handling