Update sort.textile

Changed `sort_mode` to `mode`
Update sort.textile
Update sort.textile
Update sort.textile
0.20.6 download
0.20.6 blog post
Update has-parent-query.textile
Added release notes for 0.20.6
Update geo_shape documentation for 0.90

Fixes #398
Adding new relic plugin entry to plugins guide
Converted all relative links to use absolute paths
Update geo-shape-query.textile
Fixed more guide links
Remove display list of Installed Plugins
Reverting c11db7fc570116f9269c0ed894c8f817a979719b
Updated docs on fielddata cache
Added index.fielddata.cache.expire
Merge branch 'master' of git://github.com/elasticsearch/elasticsearch.github.com into installation-preflight
Removed some documentation, as it was redundant in configuration. Reordered some paragraphs to be more readable