Merge branch 'release/0.21' into develop
bump develop version to 0.22.0-dev
update xsl_transform method to support text output
document change to xsl_transform
unit test for xsl_transform text output
set hotfix version 0.21.1
Merge branch 'develop' into hotfix/0.21.1

Conflicts:
	eulxml/__init__.py
Merge branch 'hotfix/0.21.1' into develop
set develop version back to 0.22.0 after creating 0.21.1 hotfix
add OrderedXmlObject whose constructor adds nodes in a specific order
add pypi badges (version, license, downloads)
set hotfix version 0.21.1