Feature request: determine order of channels

[clintval]

I love this plugin, so first off, thanks for the time you took to create and publish it!

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Currently the channels parameter allows one to append channels to the channel list when using conda. The code for this is here and although the language suggests addition, the action is an append:

ansible-conda/conda.py

Lines 175 to 189 in f26ac9f

	def add_channels_to_command(command, channels):
	"""
	Add extra channels to a conda command by splitting the channels
	and putting "--channel" before each one.
	"""
	if channels:
	channels = channels.strip().split()
	dashc = []
	for channel in channels:
	dashc.append('--channel')
	dashc.append(channel)
	return command[:2] + dashc + command[2:]
	else:
	return command

Using the Bioconda channel requires addition of channels in a known order so installation is predictable and dependencies are matched correctly:

❯ conda config --add channels defaults
❯ conda config --add channels bioconda
❯ conda config --add channels conda-forge

So the channels order become:

❯ conda config --show channels

channels:
  - conda-forge
  - bioconda
  - defaults

Would you be willing to support overriding of the channel order via configuration? If you have a good idea on how to achieve this I would be willing to submit a PR!