Seperates representation of package verification code and excluded files.
Adds cardinality checking for extracted license fields.

Signed-off-by: Ahmed H. Ismail <ahm3d.hisham@gmail.com>
Implements RDF Package builder.

Signed-off-by: Ahmed H. Ismail <ahm3d.hisham@gmail.com>
Implements RDF Package parser.
Implements RDF License parser.

Signed-off-by: Ahmed H. Ismail <ahm3d.hisham@gmail.com>
Adds package fields to RDF parsing example file

Signed-off-by: Ahmed H. Ismail <ahm3d.hisham@gmail.com>
Initial RDF file parser implementation.
Implements File name parsing.
Implements File type parsing.
Implements File checksum parsing.

Signed-off-by: Ahmed H. Ismail <ahm3d.hisham@gmail.com>
Changes Examples/SPDXTagExample.tag to utf-8 encoding

Signed-off-by: Ahmed H. Ismail <ahm3d.hisham@gmail.com>
Implements RDF parser and fixes issues with unicode support.

Adds files property to spdx.document which is short hand for package.files.
Fixes bug with spdx.review not returning ISO format date.
Modifies spdx.file validations to handle unicode fields.
Fixes bug with spdx.file artifact of validation where it assumed both optional fields must be present.
Updates spdx.parsers.rdf documentation.
spdx.parsers.LicenseParser handle_lics function now handles extracted licenses.
spdx.parsers.FileParser changes:
    Implements p_file_lic_conc.
    Implements p_file_lic_info.
    Implements p_file_comments.
    Implements p_file_cr_text.
    Implements p_file_artifact.
    Implements p_file_comment.
    Implements p_file_notice.
    Implements p_file_contributer.
    Implements p_file_depends.
    Implements helper function get_file_name.

Implements spdx.parsers.ReviewParser.

spdx.parsers.Parser parse function now uses spdx.document validations to check
correctness of model.

spdx.parsers.tagvalue now correctly handles unicode files.

spdx.builders.rdfbuilders changes:
    Implements FileBuilder.
    Implements ReviewBuilder.

Fixes bug in spdx.builders.tagvaluebuiders where some characters were ignored in
person and organization name entity.

spdx.writers.tagvalue now correctly handles unicode.
spdx.parsers.validations now correctly handles unicode.

Signed-off-by: Ahmed H. Ismail <ahm3d.hisham@gmail.com>
Updates README files and example files.
Adds new example file rdf_to_tv.py.

Signed-off-by: Ahmed H. Ismail <ahm3d.hisham@gmail.com>