Dalvik .dex files can also serve as APK containers so restrict the narrower...

Dalvik .dex files can also serve as APK containers so restrict the narrower identification of .dex files to files ending with this extension, and widen the identification of APK files to when file(1) discovers a Dalvik file. (Closes: Debian:#884095, #28)

This is essentially functionally equivalent (yet superior to) always
identifying files named *.apk as APK containers or adding a command-line switch
to "force" identification.

This is not a bug in file(1) as the files do legitimately differ in their
magic numbers:

    $ xxd HelloWorld.apk | head -n1
    00000000: 504b 0304 0a00 0000 0800 c907 c37d 8dea  PK...........}..

    $ xxd helloworld-janus.apk | head -n1
    00000000: 6465 780a 3033 3500 b5f7 4441 c609 399e  dex.035...DA..9.