Pyitect v2.0.0

This is a large and API incompatible update

Aquick list of changes

• supports Python 2.6+
• now uses pyitect.imports for import time plugin loading
• version postfixes are replaced with component subtypes
• Uses SemVer processing via python-semanticversion project
• module overlap is prevented with unique model names in sys.modules
• no import modes, uses imp module for everything >= 3.3 and importlib for 3.4+
• ability to store global system instance in pyitect module
• support YAML for plugin configuration files
• Custom Exception classes with exception chain support
• fully fledged docs