Patch for NEXUS-6185 Timestamped M2 Snapshots should be consumable over M1 shadow

Signed-off-by: Tamas Cservenak <tamas@cservenak.net>
Patch for NEXUS-6185 Timestamped M2 Snapshots should be consumable over M1 shadow

Signed-off-by: Tamas Cservenak <tamas@cservenak.net>
NEXUS-6185: Applied fixes

Changes:
* reformat of code
* removal of irrelevant comments and javadoc tags
* removal of added dependency in POM, is coming as transitive
* UT made one class, dummy repo made inner of UT

No code change happened to original changes (not counting
the move of dummy repo into UT class)
add filter to strip out WWW-Authenticate headers in responses when request has "X-Requested-With: XMLHttpRequest" header to avoid browser BASIC auth dialogs.
extract method from anonymous class for testing
notes
add basic sanity check of omission logic
tidy stupid default param name that annoys me
notes
Use user-agent instead of X-Requested-With to determine if WWW-Authenticate should be omitted
notes
notes
Merge pull request #294 from sonatype/NEXUS-6185-m2-snap-m1-shadow

NEXUS-6185: Timestamped M2 Snapshots should be consumable over M1 shadow
Ignore Yum ITs if createrepo is not present
update xstream
Sort discovered web-resources paths when logging debug
[NEXUS-6196] update path used by icons
Normalize (most) doc bundle configuration
Merge pull request #301 from sonatype/ignore-yum-tests

Ignore Yum ITs if createrepo is not present
NEXUS-6197: LVO should upgrade model version 1.0.0

Even if it is "old" and should be de-supported by
work done in NEXUS-6099, it seems LVO model version
was not really managed by Nx, and we still have
instances that are 2.x but LVO XML model version
is left at 1.0.0.

This change will just treat 1.0.0 as 1.0.1 as
those two are compatible (latter got new fields
with default values).

Added UT to exercise upgrades from 1.0.0 and
1.0.1.