Feature to set output location to save map

**Problem:**
The current save_to_html function does not take in location to store output. Hence I cannot organize my output html files to a specific output folder and need to write more code.

**Solution:**
A paramter in save_to_html to take in relative location of where the html file has to be stored.

**Example Syntax:**
map_1.save_to_html(file_name='first_map.html',output_location='./output/')