Update README.md with conda instructions

# CSM-CameraModel

## Building with conda

Install conda if you do not already have it.

```bash

wget https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh -O miniconda.sh;

bash miniconda.sh -b

```

> You can add a `-p <install-prefix>` to choose where to install miniconda. By default, it will install it to `$HOME/miniconda3`.

### Setting up conda for bash

Copy and paste the following into a terminal running the `bash` shell:

```bash

echo -e "\n\n# Adding miniconda3 to PATH" >> $HOME/.bashrc && \

echo -e "export PATH=$HOME/miniconda3/bin:\$PATH" >> $HOME/.bashrc && \

source $HOME/.bashrc && \

which conda

```

> [bash installation reference](https://conda.io/docs/user-guide/install/linux.html "Reference to bash conda install")

### Setting up conda for tcsh

Copy and paste the following into a terminal running the `tcsh` shell:

```tcsh

echo  "\n\n# Setting up miniconda3 for tcsh" >> $HOME/.cshrc && \

echo  "source $HOME/miniconda3/etc/profile.d/conda.csh > /dev/null" >> $HOME/.cshrc && \

source $HOME/.cshrc && \

which conda

```

> [tcsh installation reference](https://github.com/ESMValGroup/ESMValTool/issues/301 "Reference to tcsh conda install")

### Creating an isolated conda environment

Run the following commands to create a self-contained dev environment for CSM-CameraModel (type `y` to confirm creation):

```bash

conda create -n csmdev -c usgs-astrogeology cmake libcsm

```

#### Activating the environment

After creating the `csmdev` environment and installing cmake and libcsm into it, we need to activate it. Right now, cmake, libcsm, and their dependencies are isolated to a conda environment and we need to tell conda that we want to use it. The activation command depends on your shell.

* **bash**: `source activate csmdev`

* **tcsh**: `conda activate csmdev`

After you've set up conda, you can build CSM-CameraModel:

```bash

```

---

## Building without a package manager

To build:

1. Install [libcsmapi](https://github.com/sminster/csm "CSM API")

2. Install cmake >= 3.10

```bash

cd $HOME

wget https://cmake.org/files/v3.10/cmake-3.10.0-Linux-x86_64.tar.gz

tar xzf cmake-3.10.0-Linux-x86_64.tar.gz

rsync -azv cmake-3.10.0-Linux-x86_64/ $HOME/csmenv/

wget https://cmake.org/files/v3.12/cmake-3.12.0-Linux-x86_64.tar.gz

tar xzf cmake-3.12.0-Linux-x86_64.tar.gz

rsync -azv cmake-3.12.0-Linux-x86_64/ $HOME/csmenv/

echo -e "\n#Prepending csm env to path\nsetenv PATH "$HOME/csmenv/bin:$PATH" >> $HOME/.cshrc

source $HOME/.cshrc

```