2.0.0

Allows Subject to have multiple roles
Errors API changes:
- AccessDeniedError now has Reasons property, containing one or more PermissionErrors describing what exactly went wrong
  for every Role of the Subject and Action in the Request
- PermissionError now has ConditionErrors property, containing zero or more ConditionNotSatisfiedErrors describing Condition failures for given Permissions
properties of AccessDeniedError and PermissionError are now public
Allows to perform complete validation when AccessRequest.CompleteValidation is set to true
- Defaults to false (fail-early strategy)
- When using CompleteValidation, all Policy errors will be collected and returned at once, instead of failing on
  first encountered Policy error

Release notes from commits

feat: handling multiple roles by @el-mike in #49
feat: adding validation strategy option, handling errors in complete validation mode by @el-mike in #50
chore: adding integration test for complete validation strategy" by @el-mike in #51
chore: error messages updates, readme update by @el-mike in #53
chore: readme update by @el-mike in #52
feat: updating errors api by @el-mike in #54
chore: documentation updates by @el-mike in #55

Full Changelog: v1.0.2...v2.0.0