many fixes for lint and context.Context usage (#5)

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

cache/cache.go

@@ -1,24 +1,29 @@
 // Package cache is a caching interface
 package cache
 
+import "context"
+
 // Cache is an interface for caching
 type Cache interface {
 	// Initialise options
 	Init(...Option) error
 	// Get a value
-	Get(key string) (interface{}, error)
+	Get(ctx context.Context, key string) (interface{}, error)
 	// Set a value
-	Set(key string, val interface{}) error
+	Set(ctx context.Context, key string, val interface{}) error
 	// Delete a value
-	Delete(key string) error
+	Delete(ctx context.Context, key string) error
 	// Name of the implementation
 	String() string
 }
 
+// Options struct
 type Options struct {
-	Nodes []string
+	Nodes   []string
+	Context context.Context
 }
 
+// Option func
 type Option func(o *Options)
 
 // Nodes sets the nodes for the cache