qtconsole: Add vi-like key bindings to pager (fixes #6590)

Since _event_fileter_page_keypress() already exists in ConsoleWidget
class of qtconsole, that change was pretty easy and isolated. We emulate
up/down arrow keys with k/j when we use pager.
Fix conflict with d1305d7510cc3
Merge pull request #6650 from jdfreder/widg_int_test

!! Fix Travis
pin less to less than 1.7.5

1.7.5 drop all vendor-prefixed values that are set to the default value
of most browser leading to huge change in the number of lines in css and
pain everywhere.
Merge pull request #6658 from Carreau/less-175

pin less to less than 1.7.5
Merge pull request #6643 from JIghtuse/upstream

qtconsole: Add vi-like key bindings to pager (fixes #6590)
remove path from external
move pickleshare to external

can remove and make a dependency when pickleshare installs on 3.4 (should be 0.5)
remove decorator from external
remove appnope from external

make it a dependency on OS X
remove pexpect from external

make it a dependency on non-Windows
remove simplegeneric from external

make it a dependency
travis: install ipython[all] with pip

rather than explicit dependency installation