debian/: fix some lintian warnings/errors

- Remove `Testsuite: autopkgtest` from control, as this is detected
  automatically now.

- Change watch url to https instead of http.

- Make sure `/bin` is in the PATH before `/usr/bin` on Debian, lintian
  complains if the shebang is `/usr/bin/ash` rather than `/bin/ash`.

debian/control

@@ -3,7 +3,6 @@ Section: text
 Priority: optional
 Maintainer: Rafael Kitover <rkitover@gmail.com>
 Build-Depends: debhelper (>= 9), ash, pandoc, sharutils
-Testsuite: autopkgtest
 Standards-Version: 3.9.8
 Homepage: http://github.com/rkitover/vimpager
 Vcs-Git: https://github.com/rkitover/vimpager.git

debian/watch

@@ -1,4 +1,4 @@
 # Compulsory line, this is a version 3 file
 version=3
 
-http://github.com/rkitover/vimpager/releases /rkitover/vimpager/archive/(.*)\.tar\.gz
+https://github.com/rkitover/vimpager/releases /rkitover/vimpager/archive/(.*)\.tar\.gz

inc/prologue.sh

@@ -1,6 +1,12 @@
 # try to find a better shell, especially on Solaris
 
 PATH="$PATH:/usr/local/bin:/opt/csw/bin:/opt/local/bin:/usr/xpg6/bin:/usr/xpg4/bin:/usr/dt/bin:/usr/bin:/bin"
+
+# debian lintian bitches if /usr/bin/ash is used instead of /bin/ash
+if [ -f /etc/debian_version ]; then
+    PATH=$(echo "$PATH" | sed 's,/usr/bin,/bin:/usr/bin,')
+fi
+
 export PATH
 
 if [ -z "$POSIX_SHELL" ]; then