Refinements on __apt_source & --signed-by

Allow multple GPG keys/keyrings to be specified, and also include them
for the source repositories (deb-src lines).

Also fix cases where we ended up with extra leading/trainling or double
space character(s) between parts of the config line.

cdist/conf/type/__apt_source/files/source.list.template

@@ -2,6 +2,8 @@
 set -u
 
 entry="$uri $distribution $component"
+options="$forcedarch $signed_by"
+options=${options## }; options=${options%% }
 
 cat << DONE
 # Created by cdist ${__type##*/}
@@ -9,8 +11,8 @@ cat << DONE
 #
 
 # $name
-deb ${options} $entry
+deb ${options:+[${options}] }$entry
 DONE
 if [ -f "$__object/parameter/include-src" ]; then
-   echo "deb-src $entry"
+   echo "deb-src ${signed_by:+[${signed_by}] }$entry"
 fi

cdist/conf/type/__apt_source/man.rst

@@ -24,7 +24,7 @@ arch
    set this if you need to force and specific arch (ubuntu specific)
 
 signed-by
-   provide a GPG key fingerprint or keyring path for signature checks
+   provide a GPG key fingerprint or keyring path for signature checks. May be repeated.
 
 state
    'present' or 'absent', defaults to 'present'
@@ -68,6 +68,7 @@ EXAMPLES
 AUTHORS
 -------
 Steven Armstrong <steven-cdist--@--armstrong.cc>
+Daniel Fancsali <fancsali--@--gmail.com>
 
 
 COPYING

cdist/conf/type/__apt_source/manifest

@@ -31,11 +31,11 @@ fi
 component="$(cat "$__object/parameter/component")"
 
 if [ -f "$__object/parameter/arch" ]; then
-   options="arch=$(cat "$__object/parameter/arch")"
+	forcedarch="arch=$(cat "$__object/parameter/arch")"
 fi
 
 if [ -f "$__object/parameter/signed-by" ]; then
-   options="$options signed-by=$(cat "$__object/parameter/signed-by")"
+   signed_by="${signed_by:${signed_by} }signed-by=$(cat "$__object/parameter/signed-by")"
 fi
 
 if [ "$options" ]; then

cdist/conf/type/__apt_source/parameter/optional

@@ -2,4 +2,3 @@ state
 distribution
 component
 arch
-signed-by

cdist/conf/type/__apt_source/parameter/optional_multiple

@@ -0,0 +1 @@
+signed-by