Ufolint

- v1 release
- broadened pinning of Python dependency versions
- updated build dependencies to current release versions
- test against pinned dependency versions in tox CI testing

- package wheel for Python 3 only

- converted from `ufoLib` to `fontTools.ufoLib` dependency
- add requirement for `fontTools` library v4.0.0 (first Python 3.6+ only release)
- dropped support for Python 2.7
- dropped support for Python 3 versions < 3.6
- setup.py overhaul with new Python 3.6+ Python interpreter requirement
- add fontTools [ufo] extras dependencies to requirements.txt
- switched Py2 `basestring` type to `str` type in `ufolint.validators.typevalidators` module
- removed Py2 `plistlib.readPlist` in `ufolint.controllers.runner` module
- removed Py2 `xml.etree.CElementTree` in `ufolint.validators.plistvalidators`
- removed Py2 `xml.etree.CElementTree` in `ufolint.validators.xmlvalidators`
- PEP8 Python source formatting changes
- add Makefile
- remove unnecessary shell scripts (functionality replaced by Makefile)
- update MANIFEST.in file paths
- changed Python interpreter version in tox.ini configuration file

- improved error messages on \*.glif file test failures
- added CONTRIBUTORS.md documentation
- modified copyright in license and in-application help to "Source Foundry Authors"

- force install of ufoLib dependency at version >= 2.2.0. This is release where optional validation support introduced and code in this project was modified to support the changes in ufoLib

- updated ufoLib dependency to v2.3.2