Add OSGi support

[io7m]

This change moves to using the biz.aQute.bnd Gradle plugin to
produce OSGi-compatible manifests in jar files. Currently, only the
org.agrona.core module has been updated to provide OSGi metadata
because the Agrona agent should never need to be visible inside an
OSGi container. Care has been taken to preserve the existing defined
manifest fields (Automatic-Module-Name, Implementation-Title, etc).

[io7m]

I think static.javadoc.io is having problems today. I saw a couple of failures like this when I built locally, but they stopped occurring when I built on my own Travis CI account.

[mjpt777]

what does this mean for the manifest in the normal Jar?

[io7m]

what does this mean for the manifest in the normal Jar?

I've preserved the properties you were using in the jar and this adds extra OSGi headers on top. This was your old jar manifest (agrona 1.0.3):

$ bnd print agrona-1.0.3.jar 
[MANIFEST agrona-1.0.3]
Automatic-Module-Name                    org.agrona.core                         
Implementation-Title                     Agrona                                  
Implementation-Vendor                    Real Logic Limited                      
Implementation-Version                   1.0.3                                   
Manifest-Version                         1.0

This is the manifest now:

$ bnd print ./agrona/build/libs/agrona-1.0.4-SNAPSHOT.jar
[MANIFEST agrona-1.0.4-SNAPSHOT]
Automatic-Module-Name                    org.agrona.core                         
Bundle-ManifestVersion                   2                                       
Bundle-Name                              org.agrona.core                         
Bundle-SymbolicName                      org.agrona.core                         
Bundle-Version                           1.0.4.SNAPSHOT                          
Export-Package                           org.agrona;uses:="org.agrona.concurrent,sun.misc";version="1.0.4",org.agrona.collections;version="1.0.4",org.agrona.concurrent;uses:="org.agrona,org.agrona.concurrent.status";version="1.0.4",org.agrona.concurrent.broadcast;uses:="org.agrona,org.agrona.concurrent";version="1.0.4",org.agrona.concurrent.errors;uses:="org.agrona,org.agrona.concurrent";version="1.0.4",org.agrona.concurrent.ringbuffer;uses:="org.agrona,org.agrona.concurrent";version="1.0.4",org.agrona.concurrent.status;uses:="org.agrona,org.agrona.collections,org.agrona.concurrent";version="1.0.4",org.agrona.console;version="1.0.4",org.agrona.generation;uses:="javax.tools";version="1.0.4",org.agrona.hints;version="1.0.4",org.agrona.io;uses:="org.agrona";version="1.0.4",org.agrona.nio;version="1.0.4",org.agrona.sbe;uses:="org.agrona";version="1.0.4"
Implementation-Title                     Agrona                                  
Implementation-Vendor                    Real Logic Limited                      
Implementation-Version                   1.0.4-SNAPSHOT                          
Import-Package                           javax.tools,org.agrona,org.agrona.collections,org.agrona.concurrent,org.agrona.concurrent.status,org.agrona.hints,sun.misc,sun.nio.ch
Manifest-Version                         1.0                                     
Require-Capability                       osgi.ee;filter:="(&(osgi.ee=JavaSE)(version=1.8))"

All of these properties are ignored by anything that isn't either an OSGi tool, or an OSGi container. By publishing an Automatic-Module-Name entry, you're implicitly stating that all packages are exported, so I exported all packages via OSGi's Export-Package header too.

[mjpt777]

Thanks. That makes sense. I'm merge when javadoc.io lets the tests complete.