IMedia: Introduce a dummy isAvailable method

This is meant to be then plugged with removable devices

include/IMedia.h

@@ -66,6 +66,7 @@ class IMedia
         // This is likely to be used for album arts as well.
         virtual const std::string& snapshot() = 0;
         virtual unsigned int insertionDate() const = 0;
+        virtual bool isAvailable() const = 0;
 };
 
 #endif // IFILE_H

src/Media.cpp

@@ -232,6 +232,11 @@ unsigned int Media::insertionDate() const
     return m_insertionDate;
 }
 
+bool Media::isAvailable() const
+{
+    return true;
+}
+
 void Media::setSnapshot( const std::string& snapshot )
 {
     if ( m_snapshot == snapshot )

src/Media.h

@@ -93,6 +93,7 @@ class Media : public IMedia, public DatabaseHelpers<Media, policy::MediaTable>
         virtual std::vector<AudioTrackPtr> audioTracks() override;
         virtual const std::string& snapshot() override;
         virtual unsigned int insertionDate() const override;
+        virtual bool isAvailable() const override;
         void setSnapshot( const std::string& snapshot );
         bool save();