NEXUS-5944: Extract "page" utility from AR

AR has a bunch of utilities, one of the is Page,
that offers higher (read simpler) level of operations
against remote HTTP servers.
NEXUS-5944: Handle when remote is Nx repo with browsing disabled

Using Page utility to figure out what remote is.
Add IT
NEXUS-5944: Obey truststore
NEXUS-5944: No, you are wrong

These IT classes were NOT copied from SP ITs.
Not a chance. Look how method names differ!
Merge remote-tracking branch 'origin/master' into NEXUS-5944-no-browsing-allowed
NEXUS-5944: Fix IT

Not using central but rather releases as central indexes
caused timeout in IT
Merge pull request #192 from sonatype/NEXUS-5944-no-browsing-allowed

NEXUS-5944: Repository is auto-blocked if "allow file browsing" is disabled on remote