Add the option that help us to add the current directory  to include paths recursively

I wanted to add the current directory and the sub directories to search paths recursively, so I added the 2 options.  

```
# If clang should include current directory recursively.
let g:clang_complete_include_current_directory_recursively = 1
```

```
# If you are using g:clang_complete_include_current_directory_recursivel option, 
# this option allows you to specify the directories that you want to ignore. 
let g:clang_complete_ignore_include_directories = ["^\.git", "\.xcodeproj"]
```