Pull request to update for supporting LCP

[fasooDev6]

I send a pull request for SDKLanucher-Android for supporting LCP.

The following are summary for changed files:
ContainerList.java

1. if(container == null)
   • If container is null, stop processing intent and show the error message
2. class OpenBookOnThread extends Thread
   • We have changed the way of opening EPUB by processing in separate thread.
     Because LCP needs to popup pass-phrase dialog-box waiting user input in the Readium SDK, which does not work in the same thread.
3. private void containerRegisterContentModules(Context context)
   • We added containerRegisterContentModules to invoke Drminitialize.
     If user wants to include the DRM feature into the Launcher, call this method before the opening container in the "OpenBookOnThread".

DrmInitialize.java

• We created one blank method as DrmInitalize.
• If user wants to include the DRM feature into the Launcher, It can be connected with DRM Initialize.

Please reper to
readium/SDKLauncher-iOS#68

[danielweck]

Note that there is a similar PR for the proposed above code change (nil container):
https://github.com/readium/SDKLauncher-Android/pull/76/files#diff-c50ac569905f558500aec3f615f04357

[rkwright]

We'll need to review this in the context of the ongoing LCP integration work