gst-element-check.m4: rename AM_GST_ELEMENT_CHECK to GST_ELEMENT_CHECK

And allow passing of a minimum version (if not needed, pass 1.0).

https://bugzilla.gnome.org/show_bug.cgi?id=682968
diff --git a/.gitignore b/.gitignore
index da9b993..32e6e3f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -37,7 +37,6 @@
 py-compile
 registry.*
 coverage-report.txt
-gst-element-check.m4
 .deps
 .libs
 *~
@@ -50,4 +49,4 @@
 *.ipch
 *.sdf
 *.opensdf
-*.DS_Store
\ No newline at end of file
+*.DS_Store