NEXUS-5861: RemoteStorageContext values might come from parent

So, wrapping the one of the 3 values as read only.
As other two (proxy and auth) are only at global level
(no more per-repo proxy, only global, and auth was never
global, only per-repo).
Merge pull request #114 from sonatype/nexus-5861-rsc-parent

NEXUS-5861: RemoteStorageContext values might come from parent
[NEXUS-5870] Allow additional LDAP environment variables to be configured via system properties

As app context is exported to system properties, use can configure them via nexus.properties

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Copy classes from pluginkit which are useful for all nexus plugins

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Merge pull request #115 from sonatype/NEXUS-5870-custom-ldap-env-vars

REVIEW: [NEXUS-5870] Allow additional LDAP environment variables to be configured via system properties
Fix license headers

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Merge remote-tracking branch 'origin/master' into nexus-5790-new-content-impl