related to issue 1708 - bugfix to allow no expiration for gae_memcache
When gae_memcache passed expiration time to memcache Client
(see commit 59290534bc2faad501ba13c495aeb051d619314),
logic is no longer needed to calculate time delta, since memcache
handles that for us.  Also, time_expire=0 was expiring values
immediately, instead of the documented behavior where 0 signified
no expiration.

Kept timestamp in value for backwards compatibility (is this
necessary since cached data is transient?)
Fix concurrency handling in order to avoid that some workers get the same task at the same time.
first steps to a cleaner DAL and rname integration
Update tr.py
Create tr.py
Merge pull request #345 from crimsoncantab/master

related to issue 1708 - bugfix to allow no expiration for gae_memcache
Merge pull request #347 from niphlod/enhancement/DAL

first steps to a cleaner DAL and rname integration
Merge pull request #348 from mbaser/patch-1

Update tr.py
Merge pull request #349 from mbaser/patch-2

Create tr.py
allow URL(...,language=...) with parametric router, thanks Jonathan
Merge pull request #346 from dokime7/master

Fix concurrency handling in order to avoid that some workers get the same task at the same time.
Update error_messages; capitalize first character

Result of a discussion: https://groups.google.com/forum/#!topic/web2py/IDkr4w_wKv4
The intent is to convert the first character of all error messages to a capital letter.
Allow empty reference field in form without IS_EMPTY_OR() validator, avoiding constraint violation exception
codemirror 3.21
fix bug related to upgrade setuptools / pip
Merge pull request #351 from kirsn/master

Update error_messages; capitalize first character
Merge pull request #352 from viniciusban/empty_reference_field

Allow empty reference field in form without IS_EMPTY_OR() validator, avoiding constraint violation exception.
Merge pull request #353 from ilvalle/create_view

codemirror 3.21
Merge pull request #354 from alfonsodg/master

fix bug related to upgrade setuptools / pip
fixed issue 1839: catch exception if source code cannot be opened in the debugger