PTFM-8759 Document module-level attribute convention
Generalize rule in f95535c
Print message when retry loop recovers; enable upgrade messages

- Make it clear when the retry loop successfully recovered a request.

- Initialize logging to include info messages (previously logging was
  initialized in app_builder as an import side effect, to include
  warning messages only). This has the side effect of re-enabling
  messages about server-side recommended upgrades.
[PTFM-13697] Skip CentOS 5.11 in applet exec test

Summary:
Skip CentOS 5.11 when remotely running applets in
test_var_initialization, since 5.11's latest official OpenSSL package
is not sufficient for building/linking apps that target Ubuntu 12.04.

Using 'dx build --remote' is the preferred alternative to attempting to
cross-compile C++ apps on old distros that lack up-to-date dxcpp library
dependencies.

Test Plan: Ran test on CentOS 5, OS X 10.9, Ubuntu 12.04

Reviewers: psung

Reviewed By: psung

Subscribers: akislyuk

Differential Revision: https://phabricator.dnanexus.com/D176
Cease building R packages for Debian
Fix condition in c56377b

Print retry success message only when all logic has completed
Fix condition in 88b1d26
Remove import-time side effects from describing job
Changelog and version updates for v0.127.0