Add 3 functions to utils_memory for getting some usage info of hugepages.

get_num_anon_huge_pages(pid) : get the anonhugepages' usage amount of a progress
get_num_huge_pages_free() : get the number of free hugepages
get_num_huge_pages_rsvd() : get the number of rsvd hugepages
When you’re done with a file, call f.close() to close it alwasy a good habit, so use ```try ... finally ...``` is suggested.
The best way to use a file though, is as a context manager:
```
with  open('/proc/%s/smaps' % pid, 'r') as f:
    # use f
``` 
which will call f.close() automatically