Add ssl_certs_file arg and config for custom ca bundles

tests/samples/configs/has_everything.cfg

@@ -13,6 +13,7 @@ include_only_with_project_file = false
 offline = false
 proxy = https://user:pass@localhost:8080
 no_ssl_verify = false
+ssl_certs_file =
 timeout = abc
 api_url = https://localhost:0/api/v1/heartbeats
 hostname = fromcfgfile

tests/samples/configs/ssl_custom_certfile.cfg

@@ -0,0 +1,18 @@
+[settings]
+verbose = true
+api_key = d491a956-c8f2-44a9-98a7-987814bd71ba
+log_file = /tmp/waka
+hide_filenames = true
+exclude =
+    ^COMMIT_EDITMSG$
+    ^TAG_EDITMSG$
+    ^/var/
+    ^/etc/
+include =
+    .*
+offline = false
+proxy = https://user:pass@localhost:8080
+ssl_certs_file = /fake/ca/certs/bundle.pem
+timeout = abc
+api_url = https://localhost:0/api/v1/heartbeats
+hostname = fromcfgfile

tests/samples/configs/ssl_verify_disabled.cfg

@@ -13,6 +13,7 @@ include =
 offline = false
 proxy = https://user:pass@localhost:8080
 no_ssl_verify = true
+ssl_certs_file =
 timeout = abc
 api_url = https://localhost:0/api/v1/heartbeats
 hostname = fromcfgfile