Stix-validator

- STIX v1.1.1 schema validation support
- Updated schema directory to include STIX v1.1.1 schemas
- Updated example profile and samples to STIX v1.1.1
- Changed behavior of `--json-results` to also set `--quiet`
- `XmlValidator.validate()` always returns a dictionary
- Fixed error that may have occurred if large instance documents were validated

- STIX v1.1 schema validation support
- Updated schema directory to STIX v1.1
- Added **experimental** support for STIX Profile conversion and validation
- Conversion from XLSX to ISO Schematron or XSLT
- Added **experimental** `SchematronValidator` and `ProfileValidator` classes to validators.py
- Added `--json-results` mode that prints validation results in JSON format
- Added `--quiet` mode that minimizes output to just the results and fatal errors
- Modified all validator classes to accept filenames, file-like objects, `etree._Element` or `etree._ElementTree` instances as `validate(...)` arguments.
- Validator `validate(...)` methods return JSON-friendly dictionaries.
- Added example STIX Profile and example instance document

STIX Document Validator v1.0 BETA