Implement shade-jar
Add manpage for shade-jar
Install shade-jar and its manpage
Revert "mvn_file: add support for absolute paths"

This reverts commit 9f136591a37fc5d2ba53d36379a1b9bb1d9c7298.
[test] Fix tests after revert of commit 9f13659
[xmvn_config] Add XMvnConfigException

Can be useful for raising incorrect configurations
[xmvn_config] Cleanup imports and possible QE problems

Unneeded semicolons
Non-raw regex strings
Unused import
[xmvn_config] Raise exception when all mvn_file paths are absolute

XMvn would fail anyway during install phase because it needs at least one
relative path
[test] modify mvn_file tests for dealing with absolute paths
[mvn_file] Catch XMvnConfigException properly and report it
Add notes about limitations of shade-jar
Preserve resource files when shading JARs