Only set the fade-all class when merging new params

Otherwise layers disappear during panning and zooming. We only want to
force fade-in of all tiles simultaneously when we are merging new params,
i.e. setting a new TIME param.
(cherry picked from commit 7261180ebe15c3d1ebe5c154d20d575dba98295e)
latest OL to get @ahocevar's fix for the element observe issue
(cherry picked from commit af07e41d4d1c4fb4785279448e31ed1bc2bd48ff)
latest OL to get @ahocevar's fix for the backbuffer sequence
(cherry picked from commit 1c07bf70164c24c8ee5fa8a34688b31aac94e8fe)
enable raster upload in importer client
(cherry picked from commit 39491927cb57d2d48fffc762a1f23e4481357d6d)
fix and use improved file handling, raster upload
(cherry picked from commit bb21a09618fccb1d1f9b539d406f6974b89a5d85)
attempt fix for opengeo/mapstory#635
(cherry picked from commit 65a82096ef89c227e42959d708f91e021df649dd)
fix for opengeo/mapstory#642
(cherry picked from commit 4b7ce36199d0de21d9d92ea4ddb417c098f7068d)
fix for opengeo/mapstory#634
(cherry picked from commit 1dfc9180b3d5592672712f287d9b311dedd48178)
check import response for multiple and bad tasks

ignore extra/unrecognized files, better messages for no recognized
files, more than one file, and potential other error in the response

refs opengeo/mapstory#364
(cherry picked from commit 5d7b9c6022c94c9ab57f19f7bbfafc0ae1ea9b7e)
follow up to 5d7b9c6 - better msg on invalid data

with the new file api, detection of invalid files happens on
python side of things
(cherry picked from commit ca2bf03f004ec2911c8b74504e48c064a7c0c5c5)
Add the last modified field to the map listing page in the django admin
(cherry picked from commit 56e670b19166922f53ed0cf59c8df0a0f7cac05b)
folow up to 5d7b9c6, refs opengeo/mapstory#364

delete any unrecognized tasks to allow import to proceed
handle user errors properly in save_step
remove unused function, minor spacing changes
(cherry picked from commit b4e36c6d292e70708d441f3613cf4ab854b4ac4a)
opengeo/mapstory#648, check csv column names
(cherry picked from commit 42a492a890196830645051c629f56a00175575ba)