all: Unify case of config variable names

All config variables starts with low-case and uses camelCase.

If there is abbreviation at the beginning of the name, the whole
abbreviation will be written in low-case.
If there is abbreviation at the end of the name, the
whole abbreviation will be written in upper-case.
For example, rssURI.

examples/blog/config.toml

@@ -1,4 +1,4 @@
-baseurl = "http://blog.hugoexample.com/"
+baseURL = "http://blog.hugoexample.com/"
 languageCode = "en-us"
 title = "Hugo Example Blog"
-canonifyurls = true
+canonifyURLs = true

examples/multilingual/config.toml

@@ -1,6 +1,6 @@
-baseurl = "http://example.com"
+baseURL = "http://example.com"
 
 [taxonomies]
 tag = "tags"
 group = "groups"
-menu = "menu"
+menu = "menu"