Added Enum type for Insertion point and a block method implementation

see
- (void) interceptMethodForSelector:(SEL)sel
interceptorPoint:(InterceptionPoint)time block:(InterceptionBlock)block;

Now gives a result like..
```
Normal proxy test (No implicit log)
------------------------------
addObject: START intercepted with custom interceptor!
removeObjectAtIndex: END   intercepted with custom interceptor!
**count START intercepted with custom interceptor!

Logging proxy test (Has inherent log)
------------------------------
addObject: START intercepted with custom interceptor!
START -[__NSArrayM addObject:] args:3 returns:v
  END -[__NSArrayM addObject:] args:3 returns:v
START -[__NSArrayM removeObjectAtIndex:] args:3 returns:v
  END -[__NSArrayM removeObjectAtIndex:] args:3 returns:v
removeObjectAtIndex: END   intercepted with custom interceptor!
**count START intercepted with custom interceptor!
START -[__NSArrayM count] args:2 returns:Q
  END -[__NSArrayM count] args:2 returns:Q
```