Changelog and version updates for v0.100.0
Include new requirements spec files
Generalize requirements file include
Eliminate use of nosetests, which has i18n bugs
Use encoding from locale (it seems to be absent as a stream attribute sometimes)
Remove debug statements that trigger encoding errors
Clear the jq directory as part of make clean
Use byte literal when scanning for newlines
Travis: run a subset of tests

Hopefully this subset is fast and lets Travis complete builds quickly.
Do not hardcode Python 2.7 in Makefile
Deactivate Travis virtualenv before running tests

This avoids interference between the Travis virtualenv and our nested virtualenv when installing packages.
When running tests, install all dependencies' executables
Add Travis badge
Add link to Travis
Use err_exit in dx_build_app
Do not allow negative runtime (due to clock skew) to be displayed

Also a minor readability improvement
Normalize formatting.
PTFM-11918 Java bindings don't retry non-retryable routes.

DXAPI.java now knows whether each route can be retried, and all other
clients e.g. apiCallOnObject also specify whether the request can be
retried.
PTFM-11917 Support 503/Retry-After in Python, Java bindings
PTFM-12009 Rename always_retry to safe_to_retry and update docs

This parameter rename better reflects the real meaning of the parameter.
always_retry has been deprecated and eliminated where possible. Changes
by language:

* documentation: update src/api_wrappers/README.md to show both names
* dxcpp: rename retry to safe_to_retry (non-breaking)
* dxpy: document always_retry but don't rename it as that would be
  breaking. Could be changed later if we provide compatibility
  translation
* dxjava: previously done
* ruby, R: no changes at this time, but could be changed later if we
  provide compatibility translation
* JS, Perl: no changes as these bindings have not implemented retry
  logic

Also: fix broken links in dxcpp doxygen.