525 combine app and core

[Task 525](https://integracredit.acunote.com/tasks/525) - combine `leads_app` and `leads_core` into `leads_service`.


### Hot it is done
I took the original leads_app/master then merged into it leads_core/master and resolved conflicts.

### Changes
* Remove `LeadsCore` namespace
* Use `leads_service` schema for models.
* Get rid of core dependecies that come from leads_app (customer_core, account_core, etc).
* Rename LeadsApp -> LeadsService
* Remove CreateLead class and 
Finished in 0.64188 seconds (files took 1.31 seconds to load)
60 examples, 0 failures

### RSpec
```
Finished in 0.64188 seconds (files took 1.31 seconds to load)
60 examples, 0 failures
```

### Doc
```
Files:          15
Modules:         2 (    0 undocumented)
Classes:        13 (    0 undocumented)
Constants:       0 (    0 undocumented)
Methods:         0 (    0 undocumented)
 100.00% documented
```