fix gpg-agent "running already" check

The GPG_ENV file is sourced before doing the gpg-connect-agent check,
but this file (unlike the SSH_ENV file) doesn't export GPG_AGENT_INFO,
so the check always fails.  This results in new gpg-agents continuously
being spawned.

All this commit does is put in the single export to fix the problem.
PLUGIN: gpg-agent: export SSH_* environment variables too

If using the gpg-agent with --enable-ssh-support, the SSH_AUTH_SOCK and
SSH_AGENT_PID environment variables need to be exported once sourced
from GPG_ENV.  Otherwise, we get no benefit from the persisting these
values to GPG_ENV; subsequent openned terminals don't see the existent
gpg-agent as a process for an SSH daemon.
Add commonly used git stash aliases
Check bundler version to avoid error with unsupported command line arguments
More expressive symbols for git and mercurial.
gitignore fix for custom folder.
Moved misplaced plugins.
Fix: Agnoster theme added venv name even if disabled
See http://www.virtualenv.org/en/latest/index.html\?highlight\=virtual_env_disable_prompt\#activate-script for info regarding this.
Add tmux aliases
Merge pull request #2107 from maxd/master

Check bundler version to avoid error with unsupported command line arguments
Merge pull request #2184 from jmagnusson/agnoster_respect_venv_disable_prompt

Fix: Agnoster theme doesn't respect VIRTUAL_ENV_DISABLE_PROMPT
Merge pull request #2192 from kevintraver/tmux-aliases

Add tmux aliases
Merge pull request #2078 from tbuehl/master

Add commonly used git stash aliases to git plugin
Merge pull request #1963 from shajra/pr/gpg-fix

fix gpg-agent "running already" check
Merge pull request #2165 from kevinxucs/custom-gitignore-fix

gitignore fix for custom folder.
Merge pull request #2138 from Profpatsch/theme-agnoster

More expressive symbols for git and mercurial.
Merge pull request #1688 from mbauhardt/z

ohmyzsh plugin of the z project: https://github.com/rupa/z
Merge branch 'master' of https://github.com/robbyrussell/oh-my-zsh