Add 3 new unit tests for arima_process: arma_acovf, arma_acf, arma_generate_sample
BUG include_package_data for install closes #907
DOC: Fix section header.
DOC: Remove unknown section title.
DOC: Cannot have arbitrary indents.
DOC: Parameter is NOT a section title.
DOC: Fix bullet lists.
DOC: Fix literal block.
DOC: Don't use substitution notation for abs.
DOC: Fix literal block issue.
GITHUB: Contributing guidlines
DOC: Add note about docs to release process.
Merge pull request #1007 from jseabold/doc-cleanup

Cleanup docs for release
Merge pull request #1005 from vincentarelbundock/contributing_guidelines

DOC: Contributing guidlines
Merge pull request #1001 from statsmodels/fix_setup_data

BLD: include_package_data for install. Closes #907
Merge pull request #817 from ChadFulton/arima_process_tests

TST: Add 3 new unit tests for arima_process.
MAINT: Add .mailmap file.
Merge pull request #1009 from jseabold/add-mailmap

MAINT: Add .mailmap file.
TST: test_diagnostic, add results with pandas, see issue #962
TST/STY delint 2 test modules (pylint false errors and warnings)