search for vcards in the chooser via '/'

this is especially useful when trying to merge a new email address into
an old vcard
changed version to 0.7 (dev)
frame around the search popup
there was an urwid class for pretty frames
Move query and sync controllers to separate modules

The time needed to import all the dependencies for both tasks is,
unfortunately, large enough to be detected by the user. By only
importing the necessary modules in the `pc_query` tool, a simple query
time was cut by half (from 800ms to 400ms). This also mean importing the
`ui` module only when necessary (when the delete option is used for the
query controller).

A controllers package is created as a container for these controller
modules.

Improves #85.
Make only one SQL query per search

Merges search() and get_vcard_from_db() into search() as it is always
needed to call the later after the former. There was really no
performance improved measured but it makes the code simpler (and it
doesn't decrease the performance either).

Improves #85.
Add new modes to query: name, fname and allnames

Previously, when using pc_query, the full vcard was searched for
matches, which can be very time consuming, specially if vcards contains
images for the contact. A new command line option and configuration
variable is added (--where and [query] where) to control where to
search. Possible options are vcard (the default and the previous
behaviour), name and fname (searching in those DB fields respectively)
and allnames (searching in both).

Using any of the options but vcard yields a reduction in search time by
almost 1/3 (400ms vs 175ms) when compared with the vcard search.

Improves #85.
Merge pull request #86 from llucax/less-import

Move query and sync controllers to separate modules
bugfix in the vcard chooser
create db directory if it doesn't exist

should fix github issue #72
bugfix: don't check resource if it doesn't exist

raised an Exception otherwise

this should fix github issue #87
Don't use account name as table name

This should fix github issue #81 .

A database reset is necessary.
While I was at it, a ctag column was added to the accounts table
pep8 fixes
better support for broken vcards (no FN prop)

We are now trying to fix vcards that have no FN (reconstruct it from the
N property).

For reference: github issue #90
always trying to fix errors in vcard

if vcards where imported from files they were not fixed before
better error logging on failure to import vcards
man pc_query: documented --where
doc update

not really, just moved some paragraphs from the README to the parts/*
file they belong in.
updated CHANGELOG
updating CONTRIBUTING, no more develop branch

Nobody was using it anways, I'll just try harder to keep the master
branch bug free.