r/squid: Support custom cache rules

Instead of hard-coding a single cache directory and a set of refresh
patterns, the *squid* role can now have custom cache rules defined with
the `squid_cache_dir` variable (which now takes a list of `cache_dir`
settings) and the `squid_refresh_pattern` variable (which takes a list
of refresh patterns).  If neither of these are defined, the default
configuration is used.

This is a breaking change, since `squid_cache_dir` used to refer to a
directory, and the previous default was to configure one cache path.
There are no extant users of this role, though, so it doesn't really
matter.

roles/squid/templates/squid.conf.j2

@@ -78,11 +78,18 @@ maximum_object_size {{ squid_max_object_size }}
 cache_replacement_policy {{ squid_cache_replacement_policy }}
 
 # Uncomment and adjust the following to add a disk cache directory.
-cache_dir {{ squid_cache_dir_type }} {{ squid_cache_dir }} {{ squid_cache_dir_max_size }} {{ squid_cache_dir_l1 }} {{ squid_cache_dir_l2 }}
+{% if squid_cache_dir is not defined %}
+#cache_dir ufs /var/spool/squid 100 16 256
+{% else %}
+{% for item in squid_cache_dir %}
+cache_dir {{ item }}
+{% endfor %}
+{% endif %}
 
 # Leave coredumps in the first cache dir
 coredump_dir /var/spool/squid
 
+{% if squid_refresh_pattern is not defined %}
 # Never cache objects from internal servers
 refresh_pattern \.{{ ansible_domain|replace('.', '\\.') }}	0	0%	0
 # Never cache Yum repository metadata files
@@ -94,3 +101,8 @@ refresh_pattern ^ftp:		1440	20%	10080
 refresh_pattern ^gopher:	1440	0%	1440
 refresh_pattern -i (/cgi-bin/|\?) 0	0%	0
 refresh_pattern .		0	20%	4320
+{% else %}
+{% for pattern in squid_refresh_pattern %}
+refresh_pattern {{ pattern }}
+{% endfor %}
+{% endif %}