Changing case of all URLs in the website source code from Sentence to Lower

I only want to change case (Mixed to small) of URL in HREF attribute, nowhere else. This is just for convention purpose.
eg changing
 
Its <a href="http://www.abc.com/S pecial-E dition.aspx">Special Ediation</a>. 
View <a href="http://www.abc.com/O ther-N ews.aspx">Other News</a>.
 
to
 
Its <a href="http://www.abc.com/s pecial-e dition.aspx">Special Ediation</a>. 
View <a href="http://www.abc.com/o ther-n ews.aspx">Other News</a>.
...