Add a link to Tarantool 1.5 web site.

doc/{branch}/... -> doc/...
Master/Stable -> One-page/Multi-page

Update mans, docs.

A lot of resources still need to be updated (build scripts, etc).

 * Install *.lua modules into ${DATADIR}/tarantool/1.5
    and *.so modules into ${LIBDIR}/tarantool/1.5
 * Fix default package.path and package.cpath
 * Install Lua headers to ${INCLUDE_DIR}/tarantool/1.5
 * Install config.h to ${INCLUDE_DIR}/tarantool/1.5
 * Add a new package - tarantool-dev (server development headers)
 * Use RPM Macroses in rpm.spec
 * Fix tarball generation for Debian
 * Use GNUInstallDirs.cmake to setup directories

This patch explicitly saves Exception to a thread-local variable inside
struct cord on tnt_raise(). This variable can be used to safetly
re-throw last exception from any place (not only from catch() block).
This technique requires exception to be thrown and catched by pointers.
tnt_raise macros was rewritten and all 'catch (Exception &)' blocks were
substituted with 'catch (Exception *e)'.

This patch also adds a new feature to box.raise() function.
When called without arguments box.raise() re-throws last exception (if
any).

These changes needed to implement proper handlings of exception for FFI
calls.

- Drop GE/LE iterators for HASH-index.
- min/max can receive key.
- fix all tests.

+ use luaL_ref/luaL_unref to store lua scalar instead lua metatable.
+ add :is_closed method.