always use source lookup in genericFunctionQuery

-> where substr(analyzed_text, 1,1) = 'x'

threw GroupByOnArrayUnsupported exception, now it works
correctly using source lookup
write changes entry for 7dcf68b136abfa55d45e5985eb77d5fb42f71d9d
best practice for migrating from mysql
updated changelog according to 0.45.2 release
add mongodb migration docs
update readme
added more examples for string literals

link to csv2json.py in mysql best practice
added note that the admin interface runs on each node
Merge pull request #1314 from crate/h/obj-literal

object literal example and other documentation improvements
restructure develop.rst and extend contribute.rst
added documentation for table column policy
add columnPolicy property to TableInfo
implemented creating tables with 'strict' or 'dynamic' column_policy
added partitioned table integration tests
made ReferenceInfo use new ColumnPolicy enum
Added support for column_policy in ALTER TABLE
added support for reseting column_policy
rebased master into strict table
added changes for column policy
wip
blob tests