Add proper license and copyright headers to all source files

[steven-esser]

Look at https://github.com/nexb/scancode-toolkit for examples. We can reuse the copyright and license header from there.

[johnmhoran]

@MaJuRG @pombredanne @mjherzog and others: Here's a draft license/copyright header for DeltaCode source files that's based on the ScanCode cli.py header. Please let me know if you have comments (e.g., is DeltaCode a "code scanning tool"?).

#
# Copyright (c) 2017 nexB Inc. and others. All rights reserved.
# http://nexb.com and https://github.com/nexB/deltacode/
# The DeltaCode software is licensed under the Apache License version 2.0.
# Data generated with DeltaCode require an acknowledgment.
# DeltaCode is a trademark of nexB Inc.
#
# You may not use this software except in compliance with the License.
# You may obtain a copy of the License at: http://apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software distributed
# under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
# CONDITIONS OF ANY KIND, either express or implied. See the License for the
# specific language governing permissions and limitations under the License.
#
# When you publish or redistribute any data created with DeltaCode or any DeltaCode
# derivative work, you must accompany this data with the following acknowledgment:
#
#  Generated with DeltaCode and provided on an "AS IS" BASIS, WITHOUT WARRANTIES
#  OR CONDITIONS OF ANY KIND, either express or implied. No content created from
#  DeltaCode should be considered or used as legal advice. Consult an Attorney
#  for any legal advice.
#  DeltaCode is a free software code scanning tool from nexB Inc. and others.
#  Visit https://github.com/nexB/deltacode/ for support and download.
#

[mjherzog]

please change
DeltaCode is a free software code scanning tool from nexB Inc. and others.
to
DeltaCode is a free and open source software analysis tool from nexB Inc. and others.

[johnmhoran]

Done. Thank you @mjherzog .

[steven-esser]

merged #24, closing.