Improve logging

[gnieto]

While I was adding tests to apktool manifest parsing, I saw that 'Config' is passed sometimes to only forward the 'is_verbose' parameter.

With this changes it should be able to get rid of having to pass that struct to some parts of the apliaction. Also, it will make easier to add debug information (I've added a quick example for the apktool manifest parsing: check the second commit).

I understand that maybe you don't like this approach, so, feel free to close the PR :) On the other hand, if you like it, I can modify the calls to 'print_warning' and 'print_error' to remove the 'is_verbose' parameter.

[gnieto]

@Razican So, you are suggesting to change all the:

if is_verbose { print_vulnerability(...) }

to

print_vulnerability(...)

no?

[Razican]

@gnieto right, and the if can be done the first ting inside the function.

[gnieto]

@Razican Done :)