Remove some useless quotes

Bash interprets ${...} variables inside quotes as well, so just a single
set of quotes around everything should do.
Don't add reload_url in start-chrome-for-playr.sh

The playr_loader.html already (attempts to) add this parameter to the url.
Additionally, the current code in start-chrome-for-player.sh only
passes the reload_url parameter to playr_loader.html (which ignores
it), not the actual channel page on the server, so this parameter was
pointless.

Additionally, it seems impossible to add the reload_urlparameter here,
since if the reload_url parameter must be passed to playr_loader.html,
it must be present inside reload_url itself, which must contain another
reload_url option, etc.
Fix url encoding in playr-loader

This makes sure that:
 - Any special characters inside the channel url are escaped by
   start-chrome-for-playr.sh. Fr example,
	   homepage=http://www.example.org?x=a&y=b
   now becomes
	   playr_loader.html?channel=http://www.example.org%3Fx%3Dy%26y%3Db.
   Previously, it would become
	   playr_loader.html?channel=http://www.example.org?x=a&y=b
   which would cause the y=b parameter to _not_ be passed to
   example.org, but be ignored by playr_loader.
 - Url parameters are decoded by playr_loader.html. This makes sure the
   urlencodings made inside the channel above are properly decoded
   before passing them to the browser in window.location.
 - When appending reload_url inside playr_loader.html, use a ? or &
   depending on whether there is already a ? inside the url.
Fix adding player_id parameter

This:
 - makes sure a ? or & is used, depending on wether there are already
   parameters in the url
 - does not escape he special characters (?&=) in the url, since
   start-chrom-for-player.sh and playr_loader.html take care of that
   properly now.
 - Removes the big sed that fills in MACID, WEBCID, etc and just
   hardcodes player_id=${webc_id} since setting these variables inside
   the homepage is not part of the current and intended workflow.
Let cmdline_get always return the last matching value

Before, it would stop as soon as it found a value. However, this would
mean that it's impossible to override a value by specifying it again
later (in particular, values from the server-side config would _not_
override values from the commandline, which seems wanted).

A few other places process commandline options without using
cmdline_get, but they loop over $(cmdline) and switch on each value.
These places would see all matching values instead of just the first one
(and usually only the last one would have effect). This commit lets
cmdline_get match that behaviour, so it makes things more consistent.
Allow specifying boot_append multiple times

Previously, only one of these options would be processed and copied to
the commandline. Since you cannot add spaces inside the boot_append
option, you could only specify one commandline option in this way. By
simply processing all boot_append options, you can specify a separate
boot_append option for each commandline option that should end up on the
commandline.
Introduce keep_append option

This option works similar to the boot_append option, in that it causes
options to be appended to the commandline when generating a bootloader
configuration.

However, in addition to adding the contained option to the commandline,
the keep_append option itself is also added to the commandline again.
This means that when booting from the generated bootloader config, any
new bootloader configs generated will again have these options present
(in particular, the options inside keep_append will survive subsequent
upgrades).
Merge branch 'master' of github.com:bizplay/kiosk-os-chroot
removed debug from command line