Implement CSV export for channels and swaps

[jamaljsr]

Closes #26

Note: This branch is based on PR #41. Only the last two commits are new

This PR implements CSV exporting of channels and swaps from the client side.

Steps to Test:

1. From the Loop page, click on the download icon to export the channels
2. Open the downloaded file and verify the data is what you expected
3. Go to the History page and click on the download icon to export the swaps
4. Open the downloaded file and verify the data is what you expected

Sample File Content

channels.csv

Channel ID,Remote Pubkey,Capacity,Local Balance,Remote Balance,Active,Uptime Percent
"170424302370816","0221d0c3a8a3d810514e902abaf7f7314a151ffce722ff87244a0339cca2d63bb8","2000000","390950","1600000","true","100"
"157230162837504","02d5844e6c781cb3927e2c5ccf6a26adade03cb9fe2a05a10a2d46d50dd4f93dd9","8000000","1990829","6000121","true","100"
"150633093070848","03fd97474010e464d61a90862bae7877413248786ae4c935e692559d4742945468","10000000","4990950","5000000","true","100"
"124244814004224","03fd97474010e464d61a90862bae7877413248786ae4c935e692559d4742945468","15000000","9990950","5000000","true","100"
"163827232604160","02d5844e6c781cb3927e2c5ccf6a26adade03cb9fe2a05a10a2d46d50dd4f93dd9","12000000","8040834","3950116","true","100"
"177021372137472","0221d0c3a8a3d810514e902abaf7f7314a151ffce722ff87244a0339cca2d63bb8","1800000","1620950","170000","true","100"

swaps.csv

"ID","Type","Amount","Status","Created On","Updated On"
"cee9d20623bc62ab5d8a7349f293f889f4d0825f20c1b13c0713171c6e7eb40a","Loop Out","950000","Success","5/19/2020 2:08:49 PM","5/19/2020 2:09:14 PM"
"fde8542ae8c393418cb63dd46cb4a79191838994dfe3ab2d99b4dac19ecd26f8","Loop In","1000000","Success","5/19/2020 2:05:22 PM","5/19/2020 2:05:59 PM"