Added a section on static configurations set only at startup.
add reuseSession switch
Merge pull request #988 from lzhan/testnum

add reuseSession switch
Fixing malformed JSON.
Using Caridy's edits.
Added sections on static configurations in the context chapter and a note linking to that section from the config chapter.
Merge pull request #989 from zhouyaoji/docs_static_configs

[docs] Added a section listing the static configs that can only be set once when an app is started in a base context.
Updated config chapter.
Fixing a merge issue.
Merge commit 'efacba216f5d3aa95fae4c5656c10f1cf76da355' into docs_yui_seed_update

Conflicts:
	docs/dev_guide/intro/mojito_configuring.rst
Added pros/cons for serving YUI statically.