mod_base: Add 'filter_not' filter for inversely filtering a list
doc: Add documentation for 'filter_not' filter
mod_base: rename 'filter_not' filter to 'reject'
doc: Update documentation on 'reject' filter
mod_base: rename 'reject' filter to 'exclude'
docs: Update documentation on 'exclude' filter
mod_admin: Add class parameters to date picker, disable when not editable
travis-ci: adding early R17 release for compile-check.
travis-ci: refer to generic 17.0 release.
Issue #764
travis-ci: minor touch to trigger re-compilation..
Issue #764
core: set the  option for Erlang 17.0 and later.
Issue #764
travis-ci: remove R17 from the opt_releases tested.
Issue #764
core: recode iso639 module to UTF-8
build: Always use a downloaded rebar

Travis-CI has a rebar version in the shell path which is incompatible
with OTP 17.0.
core: Let Travis build 17.0 again (experimental)
core: use application:get_env/2 as application:get_env/3 is not available on R15
Issue #767
base/l10n/mailinglist: changes for more binary support in z_stdlib
Merge pull request #768 from mawuli-ypa/filter-not

Add exclude filter for inversely filtering a list.
Added Mawuli @mawuli-ypa to the list of authors/contributors.
core: Separate user sites, user modules and global config from the priv/ directory

Fixes #767

See https://github.com/zotonic/zotonic/issues/767 for the full
specification and discussion.

The zotonic.config file is now search for in $HOME/.zotonic/<version,
$HOME/.zotonic, /etc/zotonic/<version>/ and /etc/zotonic.

The directory where user-defined sites and modules are searched in are
now defined in the user_sites_dir and user_modules_dir config
variables. These defaults to $ZOTONIC/user/sites and
$ZOTONIC/users/modules, respectively.

The "zotonic enablesite" and "zotonic disablesite" commands are removed.

The compilation of zotonic is now handled in the zotonic_compile.erl
module instead of in the Emakefile (due to the variable nature of the
user_sites_dir we can no longer use an Emakefile with hardcoded paths).

Compilation of Zotonic is now done in a few parallel worker processes,
to speed it up.