Issue178 code coverage

Committed code includes:
*  Code coverage support
``` 
Creates coverage report based on rspecs.
Usage:
   rake coverage
Current implementation: 
   SimpleCov package.
SimpleCov suggestions:
   * see spec/spec_helper.rb file
   * SimpleCov related code must be issued before any of your application code is required
Output:
   <project root>/coverage directory containing report files will be created.
To view report:
   open in a browser <project root>/coverage/index.html file. 
```

* move all minitest tests to RSpec format

* new_spec rake task, that creates new template spec
```
Creates new template rspec file associated with provided source file.
Parameter:
  src=<path of associated source file>
  If no parameter was provided, then user will be asked to enter a source file.
Usage:  
     rake new_spec src=<path of associated source file>
     rake new_spec
     Examples:
       rake new_spec src=lib/email/email.rb
       rake new_spec
Output:
  New template rspec file will be created.
  If absent then a suite directory will be created (see examples below).
  Example:
    * rake new_spec src=lib/email/email.rb
      Suite directory will be created: spec/email/          
      RSpec file will be created: spec/email/email_spec.rb
    * rake new_spec src=lib/file_monitoring/file_monitoring.rb   
      We already have spec/file_monitoring/ directory, so no need to create new one.
      RSpec file will be created: spec/file_monitoring/file_monitoring_spec.rb
```