Release v3.20.0

This release adds enhancements, bug fixes and test improvements.

Enhancements:
 - Integrate local search script into swupd
 - Introduce new command search-file to search files in the system
 - Support machine readable output using json on all swupd commands
 - Fallback to system config for value of content and version urls and format
 - Report progress based on download size and not on number of files downloaded
 - Create three new commands to replace different usages of verify: diagnose,a
   os-install and repair

Bug Fixes:
 - Don't run update or boot scripts if they don't exist
 - Fix invalid memory access on curl hashmap usage
 - Don't try to create new threads if not supported in the system
 - Overall review and multiple fixes on standard C API function calls
 - Fix some found memory leaks

Tests/Code quality:
 - Add unit tests to functions hard to test using functional tests
 - Improve format bump functional tests to include a minversion
 - Add test for delta manifests
 - Multiple improvements in test library and travis script
 - Mutiple code rework and improvements on documentation and readability

configure.ac

@@ -2,7 +2,7 @@
 # Process this file with autoconf to produce a configure script.
 
 AC_PREREQ([2.66])
-AC_INIT(swupd-client, 3.19.0, otavio.pontes@intel.com)
+AC_INIT(swupd-client, 3.20.0, otavio.pontes@intel.com)
 AM_PROG_AR
 LT_INIT
 AC_CONFIG_MACRO_DIR([m4])