map Inf and NaN to null

JSON does not support Inf and NaN values. Currently they are just written into the JSON and JSON.parse on the client side will fail. Correct is to map them to null which will then be parsed correctly by JSON.parse on the client side.
The issue with that is that the shortcut for lists of floats might be impossible (maybe someone else with more experience in python comes up with something else?). Maybe something similar is necessary in the to_inst case, but I can not really test them.

Real world application is to process laser scans, they contain inf and nan values for some drivers if the measurements are invalid or out of range.
something messed up indentation

not sure how that could happen, worked here.
Merge pull request #117 from T045T/develop

update ROSBRIDGE_PROTOCOL.md (many-to-many topics)
Fixed typo in raising type errors.
Merge pull request #118 from jon-weisz/develop

Fixed typo in raising type errors.
Merge pull request #116 from Garfonso/patch-1

map Inf and NaN to null
Windows-related fix for PIL Image module import
Merge pull request #119 from JonathanWade/pilwinfix

Windows-related fix for PIL Image module import
Handle float infinity and NAN s
Merge pull request #120 from RobotWebTools/float_inf_handling

Handle float infinity and NAN s
make rosapis use absolute namespace
Merge pull request #122 from RobotWebTools/abolute_namespace_rosapi

make rosapis use absolute namespace
update changelog
0.6.1
Remove unused json imports; move json imports to utility

Fixes #7
upgrade tornado to 4.0.2
import backports.ssl_match_hostname 3.4.0.2
override to enable support for allowing alternate origins

To accept all cross-origin traffic (which was the default prior to Tornado 4.0), simply override this method to always return true.
Merge pull request #126 from Rayman/develop

upgrade tornado to 4.0.2
Removes EOL Groovy from Travis build.