Add ability to manage extra repo config with different way

Add ability to manage extra repo config with:
- merge strategy, when passed extra repo config will be deeply merged
with default extra repo config;
- override strategy, when passed extra repo config will be used
instead of default extra repo config;

Also add function for merging nested maps.

Change-Id: I4b672e9dd984fc82c4a5a0e1a86e93d7b1099dba
2 files changed