bug fix: implement new dict that ignores casing on key names

[nvkelso]

This didn't entirely work:
#24

Instead of being specific everywhere, make a new general dict that abstracts this.

Was:
place = dict( [ (key.lower(), value) for (key, value) in place.items() ] )

With other places that assume lowercase like:
line 180 in init.py
name = row['name'].decode('utf-8')

[nvkelso]

This also broke the export retaining the values in columns that aren't lowercase key names.

For instance, "name", "lat", "long" etc values are pushed out. But "NAME" would result in "" values in the correctly cased column (NAME in, NAME out).

"type": "Feature",
"properties": {
"sizeClass": "",
"long": -73.980019999999996,
"point_size": 8,
"name": "New York",
"UNLOCKED": "",
"font_file": "../fonts/Arial.ttf",
"zoom_start": 1,
"rank": 1,
"LABEL": "",
"STATE": "",
"LINK": "",
"joinMe": "",
"TRACKBACK": "",
"lat": 40.749980000000001,
"font_size": 9,
"REGION": "",
"population": 19040000
}
},