Gvapi

Fixed documentation and version marks

Fixed some documentation issues

**Changes:**
- Implemented CLI interface
- Documentation for CLI
- Refactored docstrings

**Changes:**
- Implemented new `savingsf` method of `Hero` class
- Refactored exceptions
- Simple bugfix in docs

**Additions of this version**:
- tests coverage up to 99%
- implemented ``Hero.goldf`` property
- implemented returning of datetime object for "completed_at" properties
- added exception for invalid God
- added examples and updated documentation
- Replaced ``TokenWasRessetted`` exception to ``InvalidToken`` exceprion

Refactored main class and updated documentation