Improve logger macros

We need to improve the logger macros to include a string formatter and also provide a macro which marks a block of code with two messages and log the messages at the beginning and the end of the block. For example:

(logger/with-debug
 "Block is about to start"
 ;; ... some code in here ....
 "Block has been finished")

It's just an example and the final macro does not have to be like it.