Leading white space standardization and minimum_yara rename

NEW FEATURES

• Leading white space standardization
  • ensures the leading white space in validated rules are the same, by default converts and '\t' characters to four ' ' characters
  • this is a configurable behavior in validator_cfg.yml

CHANGES

• changed minimum_yara to yara_version:
  • fixes a compatibility issue

BUG FIXES

• None

Metadata canonical order updated

NEW FEATURES

• None

CHANGES

• changed the canonical order of the metadata:
  • moved reference from between source and author to between report and hash

BUG FIXES

• None

Support for multiple rules per file, addition of minimum_yara metadata

NEW FEATURES

• handling multi-rule YARA files via a new yara_file_processor.py library
• string_encoding: allow of ASCII, UTF-8 or any encoding configured in: validator_cfg.yml: Default utf-8.
• added -g to yara_validator_cli.py: suppresses the generation of id, fingerprint, version, first_imported or last_modified and will return invalid of those fields are missing.

CHANGES

• @malvidin's pull request #18 and #24 have been merged in. Including many of the stylistic changes:
  • strips down the requirements.txt so that it no longer includes the items that will be installed when stix2 is installed
  • renames the cfg folder to stix2_patch
• @BitsOfBinary made the suggestion of a yara_version optional metadata entry in pull request #29.
  • incorporated as "minimum_yara" using the existing valid_version()
• more permissive values allowed for the value of info|exploit|technique|tool|malware (any non-lowercase UTF-8 characters #28 )
• more permissive author values (include special characters, eg. @, %)

BUG FIXES

• fixed the entry for source in CCCS-YARA.yml, when source = "OPENSOURCE" a reference must be provided