Improved yamail/utility

Added yamail::utility::rw_in class that can transform args in non-const
references.
Config

Rewrite OS open-file layer
fix gitignore
fix gitignore
remove build directory from repo
add build directory to .gitignore
Merge branch 'config-parser'

Conflicts:
	.gitignore
	CMakeLists.txt
	tests/CMakeLists.txt