Domain Traversal Refactoring

[subhashb]

This PR contains the following fixes:

• Changes how domain.init() traverses the file structure
• Require domain to be initialized with __file__ (Breaking Change)
• Fixed with SQLAlchemy model generation
• Fixed inconsistencies in the usage of the schema-name attribute in Models
• Cleaned up test domain initialization
• Removed naive MULTI_TENANCY implementation
• Upgraded packages

[codecov]

Codecov Report

Attention: Patch coverage is 55.55556% with 12 lines in your changes are missing coverage. Please review.

Project coverage is 84.23%. Comparing base (9955576) to head (89ce70d).

Files	Patch %	Lines
src/protean/cli.py	0.00%	8 Missing ⚠️
src/protean/adapters/repository/__init__.py	0.00%	1 Missing and 1 partial ⚠️
src/protean/adapters/repository/elasticsearch.py	50.00%	1 Missing ⚠️
src/protean/adapters/repository/sqlalchemy.py	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #398      +/-   ##
==========================================
- Coverage   84.31%   84.23%   -0.08%     
==========================================
  Files          67       67              
  Lines        5290     5297       +7     
  Branches      978      979       +1     
==========================================
+ Hits         4460     4462       +2     
- Misses        631      636       +5     
  Partials      199      199              

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